InDesign/Prepress Myths

Myth #1 – You need to always send the entire packaged InDesign file to the printer

Fact #1 – PDFs are fine as long as your have set up your file properly and there are not any changes

Myth #2 – Bigfoot uses Pagemaker

Fact #2 – While it is true that he is behind the times, he is an InDesign user. He just needs to upgrade since he is still running InDesign CS.

I'm curious about what James said about #2… because that is true in some circumstances, notably when printing to a lower-resolution printer (like under 1200 dpi). Not everyone is outputting on high-res platesetters.

But yes, there are so many myths out there. We just heard elsewhere on the forum about the old “don't use truetype” myth. That's been false for years.

I'm curious about Mike's Myth #1. Aside from the digital copiers, which seem to handle 200ppi images just fine, when is it okay to go under 300Pppi for conventional printing? I guess I missed that Mythbuster.

You rarely need more than 1.5x your halftone screen frequency (assuming you're printing to a traditional halftone screen with regularly-space spots, like in a magazine or newspaper). If you're printing at 150 lpi (lines per inch) then you almost certainly do not need more than 225 ppi images.

There's a huge difference in file size between 225 and 300, so it's useful to stay with the minimum required.

Of course, if you import a 225 ppi image and scale it up to 110%, then you have only about 200 ppi effective resolution.

With the book publishers/printers we work with, we follow their standards and the pre-sets they have provided us. I think we can't go below 268 ppi, and even then it's frowned upon. They want at least 300.

Myth: TrueType fonts are poor quality.

Fact: Font format is irrelevant. Format is not an indication of quality.

Myth: JPGs should never be used for print.

Fact: There's nothing inherently wrong with JPGs. If they don't need any work in Photoshop go right ahead and use them.

While these days I am in agreement with you Bob, there was a time when jpegs would crash the rip at my Repro house (I know this to be true as they were across the corridor from me) as did infuriatingly eps files with jpeg compression on them (yeah try finding that file at output stage back in the day).

I am not a fan of them these days as they are 'lossy' and when saved over and over by some people (arrgh!) can become quite damaged.

True type fonts have given me problems over the years in pdf output.

As I said, Tim, if they don't need any Photoshop work.

As far as JPGs and TT giving your RIP trouble, I'll go right out on that limb and blame the RIP.

Ah yeah Bob, if they are untouched then I guess they will be fine, it definitely feels wrong to me though :)

Yeah I would blame the rip and that should not be happening these days

'll be a real stick in the mud and be old fashioned and stick up for some of these “myths”.

my work uses screen rulings between 150-200 lpi, depending on the stock we're printing on. using the 1.5 x line screen, we DO need pics to be 300dpi for effective output. yes, we can get away with less, but i'd rather get higher res pics than lower res pics… can't really fix low res pics. i might add though, having a GOOD picture @ 300dpi HELPS (a blurry pic @ 300dpi still looks blurry).

“PDFs are fine as long as your have set up your file properly and there are not any changes” I agree with this, but the “set your file up properly” and “not any changes” is rare. Sometimes we do need native files because:

1) customer may be working through a third party and wants us to handle the alterations and any future use of the file (reprints or further alts in future);

2) customer's art may be poorly set up and/or require manipulation in the native file for whatever purpose, rather than mess around with acrobat or enfocus.This can be anything from tidying up inconsistent folio positions; to fixing a dieforme; changing spine widths on covers, or adding FSC logos (which is, according to the accreditation, something the printer does, not the designer).

JPGs are still LOSSY. TIFFs are (meant to be) LOSSLESS. Look, if i receive art where the links are jpgs, i'm not going to change them all to tiffs, because yes they will output fine, but if i'm setting up artwork myself and know i want those digital assets for a while, i'll use tiffs.

rant over. onto myths:

MYTH: all text must be converted to paths (i've seen this from some suppliers)

FACT: hell no! there was a point where i was receiving that many freehand files where fonts just couldn't (or wouldn't load) and without a hard copy to check to, there was no way to ensure that the fonts used were correct (customers were using freehand to make books rather than logos). that might be the only occasion where i'd ask this. for me, text/fonts are not an issue with indesign.

MYTH: for process jobs, all full colour pics must be CMYK, not RGB

FACT: in the pre-sep film days, RGB pics would come out only on the black plate. with composite rips, RGB pics came through as good as the profile that the RIP used, which for a while were fairly bad. with indesign, its possible to make a pdf and force all pics to one colour profile, meaning artwork with entirely RGB pics can have a PDF created which will make all the pics CMYK. i'd STILL prefer that people make their pics CMYK but its not the end of the world if one or two RGBs slip through now that there are two steps to force them to CMYK: indesign, and our RIP with the same profile.

You have a good grasp of the technology, Colin. However, I think the point isn't “can you” use 300 ppi or use JPG, but “must you”? I think what Mike and James and others are trying to point out is that the myths say “you must!” and the reality is that the only thing “you must” do is learn the underlying reasons, not just follow blindly. Thanks for contributing!

“keeping the links panel open slows down indesign” is valid.

how much it slows down indesign is a factor based on the location of the files and the speed of your network.

I learned this the hard way when I first started working for my current company. I would be given files created in a different city with absolute links to files on their server instead of relative links to files in a sub folder. InDesign would run like a pig when the links panel was open and it could take forever to do even simple things like scrolling with the panel open. The program would go back to normal speeds when the links panel was closed.

My solution was to never work with remote links any more. I had to change the way we did things a bit, but it was totally worth it.

As far as the 300dpi, i think still think it's the “safe” rule of thumb, absent any knowledge of the production process. But if you know what your production process is and what your end use product is, you should be able to construct a different “safe” number for your images. As Colin said, if you have a printer with a 200 line screen, you'll want 300dpi for sure. If your production device has a 150 line screen, you should be safe at 225. If you're printing to a large format printer for banners or oversized printing, you could be safe in the 100-150dpi range (depending on how close the end user will be to the final product).

Myth: 2: converting text to outlines changes the appearance of the text due to loss of kerning, hinting

Really, a myth? What has changed that lets fonts keep hinting when outlined? Does that apply only to new fonts (such as open type) or is it a function of the type engine in CS4 or what? Sometimes it would be great to outline text but I'm concerned that the quality of small type not change.

Myth: The loss of quality and the amount of compression artifacts grows exponentially every time you open an re-save an jpeg image.

Fact: The Lion's Share of quality loss happens the first time an image is compressed with jpeg algorythm. As long as you don't crop, rotate or resample the image each subsequent time you save the image again further losses approaching to zero – even if you do some color changes. The second and third time some changes may happens, but afterwards there is no additional quality loss visible an nearly not measurable.

Myth: If you get jpeg images, you should save them to tiff bevor using them in prepress.

Fact: No. The quality loss that once happens is irreversible. You just get more Megabyte. And jpeg can every prepress-key-feature (cmyk, icc-profiles, clipping-path) you need.

I'm going to go out on a limb here as well…

True Type fonts will work and almost always have worked… people didn't use them because of the RIPs inability to process them… these days they work… but people seem to be stuck in there ways…or still own the PS Library and don't want to pony up for the opentypes for no reason

Images under 300dpi can be used… sure but in most cases people don't know where the job will be printed until the last minute so 300dpi will cover every instance. I know in my case I never know until the job is complete, and I enter imprint page details… it also depends on printed stock, which could change at the printer stage so you may never know, so why risk setting up images which are borderline at best… In this day and age file size is a Myth…

So yes 300dpi is a must.

95% of these myths are the result of the pre-press RIP either too old or converting files incorrectly or just plane falling over….

@its_betty: You are correct to be skeptical of that claim. Fonts DO lose their hinting when converted to outlines, and will change when printed… on lower-resolution devices. That's the key point. James works for Sells Printing, where they have high-res platesetters, etc.. In that world, it doesn't matter so much. But on a laser printer, or even at 1000 dpi, you will likely notice the difference between hinted type and outlined type.

@Marcus: I'm going to have to disagree with you about the 300 dpi. See earlier discussions above.

David – I have it here in an email that you kindly wrote me about 2 years ago – (actually might not be an email – you may have posted it in a comment or a topic on the blog – but I've never forgotten it – I could swear it's in my email though?)

You make the PPI of your images based on the square root of 2 x the lpi = ppi. So roughly 1.5 x 150lpi = 225 ppi for the images.

And you go on to state that the square root of 2 is sufficient to deal with pixels that are rotated 45 degrees.

I have never understood this – yes the square root of 2 is 1.41 – but how does that relate to pixels rotated at 45 degrees?

The answer is probably simple and I've been trying to relate it to a far more complex reasoning – but I would appreciate your thoughts on it? I've thoroughly given up on trying to figure it out – I thought the answer would come in a Eureka moment – but everytime image resolution comes up in a topic I'm constantly reminded of this conundrum that I can't for the life of me wrap my head around.

Well – that's pretty straightforward, now I feel silly for asking, but if you don't ask you remain ignorant forever.

Thanks Mike – I'm nearly sure that wasn't on my final test in college over 4 years ago. I don't think anyone every pointed that out before, and I've read quite a few books on the subject – clearly the wrong books though.

Finally after 2 years I can have peace of mind.

Yes, that's the basic theory, Mike! Of course, few people really know what's going on inside the postscript halftoning engine (much less the APPE), so who knows what it's really doing.

I remember when I was working on Real World Scanning & Halftones (with Steve Roth, Glenn Fleishman, and Conrad Chavez) and after printing the book I noticed that there were some really weird artifacts in many of the books' low-frequency halftones — basically image details that just shouldn't be there according to the halftone theories, image details that fell between halftone cells. Well, I happened upon Chuck Geschke at a conference and showed him the book and he looked closely and told me that he had no idea why PostScript would do that in halftones… it shouldn't!

Sigh.

Well thanks for the pick-me-up, Mike. Being out of prepress for a few years and the old noggin can't remember it all.

So the basic Myth of image resolution is that it should be 2xlpi and the fact is that mathematics proves that it should be 1.41 (or the square root of 2) x lpi = dpi of your images.

And finally I've got the last piece of the puzzle to why it's 1.41 and not 2.

@David – it's unfortunate about the halftone gremlins in the printed book on the top topic of halftones and scanning – it's ironic to say the least. But I guess these things just happen from time to time – no matter how good you are, how much you know or how well you prepare, sometimes there are things just out of your control.

Well thanks for clearing up the info on the resolution question.

very much appreciated.

I pretty consistently publish stuff that is ~180 dpi because that is what advertisers send. My preflight warns me, but no one has complained about the printed version so far…

Also I recently printed a section that had a few JPGs in it. I was hesitant to do it because of the aforementioned myth, but the PDF passed the preflight and the file did not cause a problem with the RIP, and the result was fine. Smaller file size too!

One myth that I was told over and over again was that PDFs have to be saved as .EPS files before they can be placed into a layout. As it turned out, this based on the fact that printing the layout made the .EPS files look crappy because they were a low-res preview version. Unfortunately a lot of the people I work with believe that a printout is always the ultimate version of anything.

Just my two cents, but actually I think everyone is looking at this the wrong way round.

I once calculated for the line resolution that we were printing at that the dpi should be 229 dpi. I told my clients that they should put their images at 300 dpi so that if they needed to enlarge the image in Quark (this was years ago — We had Quadras then :-) ) then they would be safe.

But you must remember that in those days, everyone wanted to know the smallest resolution they could get away with, not the other way round. A 600 dpi file was huge for those computers and the RIP would take much longer to RIP a file (also images that were rotated in Quark and not pre-rotated in Photoshop also were a nightmare for the RIP). Therefore we needed to know the maximum resolution that wouldn't make the postscript file (this is pre-pdf which automatically crops and scales the file accordingly) fit onto an optical disk.

As far as how low the resolution can go really depends on the image in question, what size it's going to actually print at (a physically small image isn't going to make much of a difference), the kind of paper being used etc.

As a rule of thumb, if your image is 300 dpi, it will be fine, but if the image is for example a map with fine text which has been scanned, then I would want to scan it at the highest resolution eg 1200 dpi.

@Raphael: You have unfortunately fallen prey to the oldest myth of them all: That scanning at a higher resolution is always better. Like in the health care debate, where some folks erroneously believe that more trips to the doctor or hospital is always better. Not so.

If you scan that map at 1200 dpi, what will happen at print time? Either InDesign will downsample it to a lower resolution or the printer will (depending on your settings). When that happens, it throws away data in a non-intelligent manner, and your image just gets blurrier. Then, if you're printing with halftones, the image gets “downsampled” again in the form of being split up into halftone spots.

I have no problem with you scanning it at 1200 ppi for archival purposes! But placing a 1200 ppi image into InDesign doesn't help, it hurts.

(You also discount the issue of file size. A 5 x 7 cmyk image at 225 ppi is about 6.5 mb. Increasing it to 300 ppi raises the file size to 12 mb. If you use 1200 ppi, you suddenly have a 192 mb image to play with. That's 185 Mb of wasted data, if you're printing a magazine at 150 lpi. Ten of those images is over a gigabyte of wasted data, of course. Who cares? Disk size, file transfer time, print speeds, pdf creation time… waste not, want not.)

Raphael,

The only reason I'd scan at 1200 dpi would be if I had to enlarge the image considerably (±400%), OR … if I'm going to convert it to a pure black-and-white bitmap [*]. These can be printed at the output resolution — 2400 dpi, if you really really want super quality. 1200 dpi is usually “good enough”. What David said: grayscale and full colour images will be downsampled, for the sole reason there is no point in sending more than 300 dpi to an imagesetter. Even if you force ID to include the full resolution into the PDF, the imagesetter itself will sample only at intervals defined by its halftone interval. (Ignoring any of the RIP oddities David encountered )

The black-and-white 'trick' works because these images do not go through the halftone machinery.

[*] I should probably add that if you see only black-and-white pixels, it's not “by definition” a black-and-white image. It could be anywhere, up to 64 bit RGB plus alpha. Link Info shows what color model it really is.

Jong and David, I'm fairly certain that Raphael is NOT talking about placing/printing a 1200 ppi scan for final output! He specifically said he'd *scan* it at 1200 ppi. That would make it much easier to clean up/sharpen fine text in Photoshop. Then from that point he could convert to whatever format/rez is suitable.

Raphael also said:

As far as how low the resolution can go really depends on the image in question, what size it's going to actually print at (a physically small image isn't going to make much of a difference), the kind of paper being used etc.

This is important too, and a great point. If you've got an architectural image with lots of sharp diagonals and high contrast colors, it'd be better to err toward the high end of the res range (go with 280 rather than 220 ppi, for instance). And if it's going to print on glossy stock at a large size and be the focal point of the spread, then ramp it up to 300.

But if you've got a small head shot, or a medium landscape, 220 ppi is going to serve just as well as 300 on the same kind of paper.

AM

Anne-Marie: Totally agree!

Using the short hand term “Combination Tone” to describe an 8-bit TIFF incorporating Type/Line Art with Color/Grayscale may help to succinctly distinguish the resolution needs of this type of image compared to those of a typical photograph (clouds > architecture).

The Myth of no-more-than-300dpi (or something x LPI) for any printed 8-bit TIFF seems especially pervasive today.

Here is one enlightened printer's suggestion for Combination Tone resolutions: https://dx.sheridan.com/guideli…..tml#images

Before we get dizzy with theories of downsampling & halftone intervals, it may be easier & more accurate to look at some output.

I put up a few samples at: bit.ly/hcbcU5

MG

I see on Mark's link above that raster images should only be TIFFs. In the last couple of years I've got into the habit of, if I need to edit an image in Photoshop, saving it as a PSD file and using that in my InDesign document. Is there any reason I shouldn't do this, or is this another myth?

Maybe I'm fighting a losing battle here, but I was taught (by the old-school printer gaffer who took the production classes where I studied) that 'line' and 'halftone' were print-specific terms, 'line' referring to artwork that used only solid ink and 'halftone' to shaded or coloured work that required halftone screening. But most people I work with treat them as equivalents to 'diagram' (or 'image best suited to vector format'*) and 'photograph' (or 'image best suited to raster format') respectively. It's possible to have diagrams with different shades of grey/colour, which would need halftoning even if it's done as vector art. So I tend to avoid the terms 'line' and 'halftone' altogether, unless I'm specifically talking about screening – 'diagram' and 'photograph' is a more useful distinction and much more comprehensible to authors!

*Not necessarily an image in vector format though: we get graphs given to us as 300dpi JPEGs quite frequently!

In the File Types listed on the Digital Art Guidelines – I'd replace the sentence under Raster Images

“Digital art files should be saved as TIFF or EPS format”

to

“Digital art files should be saved as TIFF or PDF format”

Rather than EPS.

Reason:

Saving a file to EPS is fine, it will output any vectors contained in the photoshop file – but reopening the EPS will comletely flatten the file and rasterise everything.

If you save as PDF from Photoshop, it will output the vector masks, shapes, and text layers, while retaining full editablity of these features when reopened in Photoshop – as well as containing the layers.

If you save as an EPS from Photoshop (containing vector shapes, masks, or text layers) then you would need to save a layered tif, psd or PDF for editing – save yourself the hassle of multiple files for the same thing and just save as PDF – if the artwork contains vectors created in Photoshop.

If it doesn't contain these vectors created in Photoshop then a TIFF or PSD is preferred, i.e., if it's a purely raster image.

I was absolutely horrified one day when an old boss complained that it took too long to output an illustrator file to the RIP. And he came along shut down the nearly completed transfer, then opened the illustrator file in photoshop and saved it as a jpg, replaced it in the layout and then output plates.

Sure it worked faster – but I washed my hands of that particular job and put the onus on quality on him.

Right, PDF is far better in most circumstances than EPS.

And PSD is as good, if not better in many ways, than TIFF.

I'm addressing the The Myth of no-more-than-300dpi (or something x LPI) for an 8-bit (Combination Tone) TIFF.

Yes, there are better formats–application, knowledge, and workflow permitting.

I posted the link to that printer's suggestion of 500-900ppi for Combination Tone TIFF to illustrate the term. The bit.ly/hcbcU5 address is to look at the affects of resolution & line screen. In a post PDF world we may have forgotten the occasional need for high resolution TIFFS.

MG

David Blatner said:

Right, PDF is far better in most circumstances than EPS.

And PSD is as good, if not better in many ways, than TIFF.

Hi David,

Can you elaborate on in what ways PSD would be better than TIFF and what circumstances one is better than the other?

Both tiff and psd are bitmap only, both can have layers, neither support vectors. PSD supports duotone but TIFF does not. Not sure if TIFF supports layer comps; perhaps not. The main benefit for TIFF is that you could more easily import it into powerpoint or quarkxpress 4, or something like that. The main benefit of PSD is that you can just leave it in the native file format.

Here's an old blog post that discusses this (especially in comments): https://creativepro.com/why…..-tiffs.php

As for EPS vs. PDF, here's one post on the topic: https://creativepro.com/my-…..llenge.php

Excellent reasoning – thanks!

Bookmarking those two links too :D

David,
Please consider endorsing the term “Combination Tone” TIFF, and the implied desire for increased image resolution (compared to most photographs as tiffs) when preparing for print.

Debunking of the Myth of no-more-than-300dpi (or something x LPI) for *any* 8-bit TIFF will benefit the neophyte designer & the serious digital artist.

MG

I decided to write up my thinking a little more in this blog post: https://creativepro.com/tif…..pdf-vs.php

@Mark: I'm sorry, but I strongly disagree with your idea of “combination tones” requiring 500-900 dpi. If there is vector data in the file, use PDF and you'll get a combination of vector and raster data. If you need it to be all-raster, your higher-res does not (I argue) work. In your example, you're exporting from Photoshop as PDF (which maintains the vectors), then rasterizing in Photoshop! Why on earth would you want to rasterize like this in Photoshop if you wanted sharp edges?

Please understand that if you have a 500-900 ppi TIFF image, it's going to get downsampled significantly. Either InDesign will do it at print/pdf-export time, or your RIP will do it internally. If you're printing halftones, that typically means it will downsample to 2x the halftone screen frequency (lpi). Downsampling like this is usually done in a non-bicubic manner, which means your final output will be worse than if you downsample the image yourself before printing.

There is little reason to have more than 1.5x lpi in any photographic image, so if you're printing with a 150 lpi, then 225 ppi is all you need in most images. If you do have very sharp edges, then I would suggest 300 ppi.

I'm open to hearing your argument, but I'm not convinced from your samples there. There are too many variables, including your particular rip, your worfklow, etc.

David, see https://bit.ly/fM62bR

This additional page looks at type composed in PhotoShop at 300, 600, and 900ppi, saved as pixel based 8-bit TIFFs, then printed using 100 & 200lpi screens.

The purpose is to further address the Myth of no-more-than-300dpi (or something x LPI) for any printed 8-bit TIFF-including-those-with-type. The subject is relevant to anyone creating hard edged work in a pixel based environment — for whatever reason. Yes, there are better formats — application, knowledge, and workflow permitting.

According to the images I see, if type or fine line work is an element (Combination Tone) 8-bit TIFF, a 600-900ppi image resolution will alleviate some of the inherent limitations of the pixel based format, regardless of line screen.

Yes, this assumes you will not purposefully downsample for another format, or when sending to print!

What is the Source that suggests 8-bit TIFFS are downsampling to 2x lpi? Both PhotoShop composed, as well as images Rasterized from PDFs, illustrate this is not the case. (The rasterized PDF scenario may not be as rare as we would like to think. Until recently Lightning Source International did this with All non-compliant PDF book covers — and Only *Distilled* PDFs were compliant!)

I may at sometime add plain paper output from various devices, PDLs, print drivers.

Please investigate and consider endorsing the term “Combination Tone 8-bit TIFF” and the implied desire for increased image resolution (compared to most Photographs as tiffs) when preparing for print.

Thanks,
Mark Godfrey
– – –

If I have that much control over the files, I'm going to be keeping the type as vector. Otherwise, I have to deal with the raster images the author or client sends me, whatever resolution they're at. Which is better, a 300-ppi image or a 300-ppi image upsampled to 900ppi?

Mark, the article you refer to presents a solution (raising the ppi) for a nonexistent problem. Anyone who has Photoshop can output a PDF. The PDF retains all vector information as vectors, making the ppi of the file irrelevant as far as the vector (“hard edge”) data is concerned. Naturally, if you then rasterize the PDF you will destroy the vector information, but why would you do that? It's like complaining that ice cubes melt too fast when you keep them in the washing machine. The answer isn't a colder washing machine, it's “put them in the freezer.”

@orielwen: Don't upsample. Ever. You don't add any information to the image by upsampling, you just make it bigger. (There's a standing joke in the Photoshop community about the “CSI Filter”not having been invented yet. That's the one you see on TV, where some bloke with a computer takes a vague blob in one corner of the photo and turns it into a sharp image of the suspect.) Final output quality of a sharp lower resolution image is just as good (better, in most cases), than from a upsampled version of the same image, because “upsampling” is really just some algorithm filling in its best guess as to what those extra pixels might have been. It's not the real image data, the RIP has no way of knowing which pixels are original and which are bogus when it builds its half-tone screens, and you have no control over which ones it decides to keep and throw away in the process.

I do quite a bit of theater and concert promotion work, so I've become quite used to images that are way below what conventional wisdom says are minimum size/resolution, and to how good they can look in print if the contrast and tonal range are optimized.

I know, but I've tended to assume that blurry is marginally better than jaggy, so I do upsample when the author keeps sending the same low-resolution image over and over when I ask for better, and the client is beating me over the head because the printer is telling them that the images are below 300 dpi. I'm interested in this business of making them look better by adjusting the contrast and tonal range, though: do you have any links about this?

Alan,
You have no idea how many times I have recently read of people working with type in a pixel format, because — application, knowledge, or workflow preclude vector work!

As I picture their black 10 point Modern typeface at 300ppi, I advise: To alleviate some of the inherent limitations of the Tif format when type is an element, use the highest resolution you can “afford” or the highest your press/prepress will accept, hopefully 600-900ppi. (If prepress know enough to accept it, they will know not to purposefully downsample.)

The page of Rasterized PDFs illustrates No Downsampling takes place based upon Line Screen, at least using APPE2. As far as this actually being done in a dysfunctional work flow, my post above describes the book printer (volume close to a million titles a month) doing this, well into 2010, with PDFs of book covers & dust jackets not created via Distiller.

MG
– – –

Mark, I would take a guess that the people you're describing aren't the kind of folks who frequent this site. But, like David, I'd never, ever suggest to someone that upping the output resolution is a solution, or even that it is helpful. That's just validating ignorance and encouraging bad practice. One doesn't solve miseducation with further miseducation, but by pointing out the correct problem and the correct technical handling.

If a publisher wishes to rasterize a PDF, that's up to them. It's stupid (okay, it's completely retarded), but it's their choice. The answer is to educate the publisher (or just use a different one), not invent unusual solutions to a problem that shouldn't exist in the first place. Solutions like that have a nasty and inexorable habit of becoming problems in themselves, so from both a practical and a philosophical viewpoint they are a really bad idea.

Alan, I'm not promoting a workflow or format, but I am suggesting & demonstrating that some 8-bit pixel based images can benefit from resolutions of 600-900ppi, regardless of line screen. The topic being the Myth of no-more-than-300dpi (or something x LPI) for any 8-bit TIFF.

Mark

There is such a thing as “too much resolution”, it can result in unnecessary file bloat and cost you in sharpness at printing.

Mark, what we're trying to say is that while there may theoretically be situations in which it is preferable to have a 900-ppi file, for most people those situations will never come up in practice. Either your file will have been supplied by the client or author as a bitmap, in which case you're limited to whatever resolution they saw fit to give you (and I'd put money on that being 300 ppi – at best – over 90 per cent of the time); or your file is in vector format, in which case you don't need to rasterise it.

I want to back up Mark G. in one thing: Yes, I do believe that in certain situations, on certain RIPs, and with certain images that have sharp edges, higher resolution does result in what he calls a combination tone. In fact, this came up in the very first edition of my book “Real World Scanning & Halftones.” Some images, when printed as halftones, do appear to be a combination of vector and halftone artwork. That is, there are printer dots where there shouldn't be (between halftone spots).

I actually showed this to Chuck Geschke (one of the inventors of PostScript) and, if I recall correctly, he thought it was likely a bug in the halftone algorithm. That said, it does turn out to be useful because it gives a better illusion of edge detail where the halftone would ordinarily have trouble with it.

So Mark isn't crazy! But I agree with everyone else (and my earlier comments) that increasing resolution as a general practice, or even when you have these kinds of images, is not the best technique. Reasons:

• If it's rasterized, you probably don't have control over what's going to happen downstream (how do you know it's not going to get downsampled by the rip, the software, a person, etc.)?
• It's just plain easier and more straightforward to save as PDF. True, your file may be rasterized by some moron downstream, but at least you can argue that it was vector and they screwed it up. If you provide pixels, you can't argue with them.
• The “bug” of “combination tone” is not guaranteed on all RIPs. Again, halftone output should not exhibit printer dots between the halftone spots, so the fact that you're getting them is a lucky accident.
• Your file sizes are way bigger than they need to be. I just made a document with only text and vector shapes in it; it was 7 MB at 300 ppi tiff; 58 MB as an uncompressed 900 ppi tiff; 3.2 MB as an LZW compressed 900 ppi tiff; but only 188 K as a PDF. (Or 510 K if I included the psd data to make it editable in the future, which the rasterized tiff would certainly not be.)

I hope that helps!

David, not quite a ringing endorsement, but it's a start.

The *only* point I'm making is that some pixel based 8-bit images can make Good Use of 600+ppi as No Downsampling based on line screen need take place. Call it a Bug, call it a Feature, but call it typical behavior going back to PostScript Level 2 devices.

We can see from many devices that image & printer resolution play the largest part in edge definition of Solid (100%) Lines in an 8-bit TIFF with fine or course AM line screens. see https://bit.ly/fM62bR

Let's discuss the many implications & scenarios of subject appropriate resolution for pixel based images another time.

For now this thread should stop perpetuating the “no-more-than-300dpi (or something x LPI) for any 8-bit TIFF because there is downsampling based on line screen” Myth.

Mark Godfrey
– – –

Just had to join in this, mainly because I have to work with photos that are just too awful — all to do with military history, some are as old as the hills, some would you believe scanned from newspapers and so on. But the publisher seems to think that we should put the photos in because the author wants them there — printed in black and white throughout books. I have learned not to be proud and sometimes I'm forced to 'stretch' an image until it's about 170dpi. Actually it doesn't seem to print any worse than the others — rarely do I get anything of any quality. And the publisher is always in a hurry, especially when there are 3-400 photos/maps to put in a book. Ack! Just thought you'd like to know the sort of work some of us have to do?

And if you don't think this question is impolite, I was wondering if Mike Rankin is old enough to be on this list (:)) because he looks like a handsome young schoolboy … ? Hope I'm not going to get put out into the cold. I'm of the age when the policemen look like children too!

Ann