Colors on iPhone display darker than color values

I recently noticed that colors are now displaying darker on iPhone than their actual color values. (Taking an iphone screenshot of an image and using a co开发者_如何转开发lor utility show that the color values are darker). This seems to be a recent change as I have an iphone screenshot of the same image on OS 3.0. Has Apple changed the iPhone's gamma or is something else going on?

The issue turned out to be one with Snow Leopard. When images are resized in Preview under Snow Leopard, the RGB spectrum is shifted towards red.

IIRC the iPhone screenshot function saves JPEGs, which utilise lossy compression. The compression might be damaging the colour values.

If you're getting different results on different OS versions it might just be a different JPEG encoder or different configuration of it!

For best results, try taking a screenshot of large area of solid colour (32x32 pixels to be really sure, as JPEG sublocks often go to 16x16 pixels) and checking the colour value of that.