My Grayscale Images and Colors Changed Suddenly
I played with the Feather effect on one of our documents. When I applied a feather to one graphic, the feathered graphic AND the rest of the graphics on the page got lighter. In another file, applying a dropshadow caused the graphic to become lighter. What could be going on?
This is a common cry from InDesign users… “all the images suddenly changed! What happened?” You identified the cause perfectly: You added a transparency effect. When you add any kind of transparency effect — including placing an image that has tranparency in it, or using any of the features in the Effects panel — the whole spread may change because InDesign forces the display through the transparency blend space.
Each document has a blend space, which you can control in the Edit > Transparency Blend Space submenu. You should set this to your final output. If your document is destined for the screen or an inkjet printer (or perhaps even a laser printer output), then RGB is likely the best choice. If you’re printing to a press, then choose CMYK.
If you’re printing your document to press, this probably won’t make a big difference, but it can make a big difference if you’re printing to a color printer. For example, if your final output is on an inkjet printer, you may notice your colors getting dull when you print. By changing the transparency blend space to RGB, the colors should look more saturated.
As you pointed out, grayscale images seem to change the most. I think that’s because InDesign is trying to decide whether the grays should be imaged to screen as black ink or as “gray light.”
You might wonder why InDesign doesn’t always display everything through the blend space. You can sort of force it to by turning on View > Overprint Preview. When that’s on, you shouldn’t notice a change when you apply a transparency effect.