from RGB to CMYK in InDesign
I read... " InDesign recognizes the color profiles of all placed images (sRGB, Adobe RGB, ProPhoto RGB, etc.). When you export to PDF (never PNG or JPG if you're going to press -- never, ever), InDesign uses exactly the same code as Photoshop to convert RGB images to the output color space and color profile, if you output to a legacy PDF format.
That's why there is no need to convert images to CMYK before placing them in an InDesign layout. It doesn't do any harm, most of the time, but there are no advantages. Converting RGB images to CMYK adds time and two extra opportunities for error: updates to the RGB image not being kept in sync with the CMYK version, and loss of color gamut if you use the wrong CMYK color profile in the conversion."
This mean even if I am going to print a book I do NOT need to worry if the image or illustration are RGB or CMYK? Thanks if someone can help me cause I am crazy with this " problem" once I have many GGB images.
Essentially yes. InDesign, when exporting to a press-ready format, will convert RGB images to CMYK based on your assigned color profile settings.
So theoretically you could use RGB images in everything and allow Adobe and your color setting to handle all conversions. This will work.
However, in many cases you may want to verify color in an image when switching gamuts. If you have a bright, vibrant, RGB color within an image which is outside the CMYK gamut, the automated conversion will do what it can -- which may or may not be correct for that image.
It all really comes down to the level of control you want over your print production files. Automated conversion has been around for a while. However, if you really want to check color and be accurate with conversions you pretty much always need to verify colors after the conversion. In many, many cases converting from RGB to CMYk takes some "tweaking" to get colors correct. This can be especially true for many skin tones.
For my money, I manually convert RGB images to CMYK and then color correct as needed. I don't allow the Adobe automation to convert color spaces for me. "By the numbers" is almost never as accurate as a human eyeball.