I hope you understand what all of this means, in which case it should fix your problem.
If you currently use Adobe to edit images, something like Photoshop, you need to edit the color profile it is saved as. Adobe tends to automatically save as Adobe RGB, but with web browsers it tends to sway more towards needing sRGB. Here is an excerpt I copied from another website that can explain it much better than I can. I would probably end up rambling lol. :P
Color Profiles
If the colors in your uploaded images appear different from the originals, make sure you are saving your images in sRGB before you upload them. The sRGB color profile will work the best for resized images on the WordPress.com servers. Keep in mind that some sRGB images still may have slight shifts in color when they are resized on the server. If you want to make sure your colors are as close as possible to the original, upload your images in the same dimensions that you’d like to display them on your blog and insert them at full size with no image dimensions.
sRGB is a standard default color profile for the web and is the most common color space used by web servers today. Check out this explanation on sRGB vs. Adobe RGB for further details on color profiles.
The best way to do that, if you don't already know, is to go to.. File --> Save for Web and Devices --> Then Tick the Convert to sRGB tab. This is fully assuming you are using Adobe Photoshop or any other Adobe program for image editing or compressing. This should fix the color and text layered image problem as well. I'm assuming that you are flattening the image when adding text, correct? I'm not sure if that would make a huge deal, but I have had it not save the text over the image if I forget to flatten before doing so. Of course, just BE SURE to have an original saved first, because obviously flattening an image and then saving could prohibit your ability to ever revert it.
To be honest, if you do not use Adobe, I am not sure how you could attempt this just to see if it is in fact the right fix for your problem. Also, I may have typed this all for no reason if you already knew all of this, so sorry for that too. I'm really baffled at what could be causing this if this isn't the problem, just let me know so I know what to tell others if they have the same type of problem.