Pixel Format

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Hey guys, I have a question. I'm having a program that takes screenshots but I need a small file size, so I've been adjusting the Pixel format. I've been using 16 bit RGB565 and I'm just wondering if there is any advantage using RGB555 quality or file size wise? Since 1 bit is un-used, would certain compression algorithms take advantage of that? Or would both files end up the same size (after or before compression) only the RGB565 with a slight higher quality?

I've tried googling it but it seems like there isn't much answers about the certain pixel formats...

Thanks!

Posted 29-Jul-10 18:01pm

Mike$7

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Peter_in_2780 · Answer 1 · 2010-07-29T19:41:00

Solution 1

Depending on what's in your screenshots, you might get better compression by using a palette-based compression scheme. Formats like GIF can do that. For example, if there are fewer than 256 different colours on the screen (or you can force that to happen), then you can fit a pixel in one byte before compression. I don't know offhand of any code to do it, but I'm sure it's out there.

Posted 29-Jul-10 19:41pm

Peter_in_2780

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Mike$7 30-Jul-10 2:19am

Oddly, I've set the bitmap saving to .Gif and it takes more space to store a .Gif with default pixel format than to store a jpeg with 16 Bit RGB565... The pictures would be all handled by my program and there would no need for any external editors to open my file. Any other suggestions? I'm trying to find some code to save a jpeg file with selectable quality... any links that have a function to input a bitmap to save as a quality-controllable jpeg?

Christian Graus · Answer 2 · 2010-07-29T19:44:00

Solution 2

Try saving as a jpeg, that usually gives a small size. Otherwise, just save it as a GIF, as Peter said. You may need to create a 256 color image and draw your image onto it, in order to do the color reduction. Don't use any weird formats like RGB555, no standard file format uses those.

Posted 29-Jul-10 19:44pm

Christian Graus