No RGB images except NOTES layer
This check reports when the colour space used in any placed images, that are not on a NOTES layer, is set to RGB.
Pixel images that have been captured by a digital camera or a scanner will always start off as RGB images (Red, Green, Blue). Vector drawn images can also be set to use the RGB colour mode.
If an RGB image is to be used in commercial printing it is typically converted to the ink colours CMYK (Cyan, Magenta, Yellow and Black) when outputting.
The actual colour that any RGB or CMYK describes depends on many variables such as the type and setup of screen when viewing RGB images and the ink, paper and light source used when viewing CMYK images.
Unless you are working in a colour managed workflow the movement between RGB and CMYK can cause unexpected and disappointing results and one way around this is to insist that all images are converted to CMYK in the same way before they reach the InDesign page.
Fix this problem by using a CMYK version of the same images or using an alternative image.
Alternatively, if the image is not required in output, then moving an RGB image to a layer whose name starts with the word ‘NOTES’ with also pass this check. This can be especially useful when working with backlist.
Tip: It is possible to switch on a Colour Space column in the Links Panel. (InDesign Menu > Window > Links) using the Panel Options.
