Hi,guys.

Please do me a favor,someone says，the Mac OS of iPhone,could only export 65536 colors to LCD,even the LCD is 24bit capable.

His proof is,all images copied from iPhone by third-party software——including images from iTunes synced to Photo app of iPhone,is 65536 colors.even after I show him some snapshots (24bit and more than 65536 colors) took from iPhone with Power+Home way,he insist that is an Apple's trick,OS uses some cheating algorithm to fool us iPhone users.


Is he right?

Or how to prove he's wrong(with which machine or technique)?

It's well known that iPhoto sync to iTunes resizes the image to lower quality in order to save space and memory before sending the file to the iPhone. So of course those won't look as good as the originals.

As for whether or not it's really 64k colors or 16.8m colors, it doesn't really matter to anybody. It's not like the extra colors is going to make using the iPhone be a better experience.

If you wanted to try to figure it out, the easiest way is probably to take a color, like red, and then make a program that displays all 256 shades across the whole screen. Then make another app which displays 64 shades of red spread across the same distance. See if there is a difference in appearance. If there is, you're seeing 24-bit color. If there isn't, you're seeing 16-bit color.

Also, typically, LCD monitors sold which only support 18-bit color are because of the panel not because of software or video processor. So if the iPhone only supports 16-bit color, it's most likely the LCD panel itself, not the rest of the iPhone.

And no, there is no cheating algorithm for something like what you mentioned. Implementing anything of the sort would be more work than doing it right, not to mention a waste of time. A screenshot is and should be a simple framebuffer (video memory) dump with minimal processing. If you're seeing colors that only appear in 24-bit in your screenshot, all you've proven is that the iPhone's OS and GPU support 24-bit color. You haven't proven the LCD supports it.

The original-gen iPhone LCD's specs seem to claim it's only capable of 64k colors. The 3G's LCD specs state 16m for it, but who besides Apple knows for sure...

The OS could feasibly support 16m colors, but like many OSes it depends on the LCD what ends up being displayed to you.