Why would a grayscale png file change saturation next to grayscale tiff?
I have two grayscale photos placed on a page - a tif file and png file. They are close to each other with the frame edges touching but not overlapping. They appear the same in saturation and levels and 8 bits/channel, dot gain 20%. I need the two images on consecutive pages with one or two pages only needing the png file. I have pasted in place the two photos and deleted the tif image when not needed. When the tif file is deleted, the saturation of the png file visually becomes darker. It appears darker in the InDesign file and low-res PDF but appears correctly in high-res print files. If I paste the tif file back on the page (anywhere on the page) the saturation immediately lightens again. I have looked into trapping, transparency, and compared setting in Photoshop. What would cause the saturation to change with/without the tif file if both are printing as black?
