How to reduce the size of an image in C# and .NET 3.5?

Question

I have a screen shot I take in my mobile app. The screen shot takes about 32 KB when saved as a png on a disk.

I am sending these to a central SQL Server and 32 KB

Answer 1

Try converting to a pure monochrome bitmap. These are extremely small, since they only use one bit per pixel.

EDIT: I'm a liar. Just tried this in Paint and it's about 40k compared to the original 20k. I could have sworn those had massive space savings when I used them before...

EDIT EDIT: OK, apparently they do have massive savings. It's just that for these images, PNG has even more massive savings. Just tried a 16-color bitmap instead and that blew it up to 150k.

EDIT EDIT EDIT: BUT, the monochrome bitmap zips to 9k bytes, while the PNG stays at 20k even zipped.

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So, it looks like if you want to go the compression route, you can first convert to monochrome bitmap, then compress for images around half the size of the PNG.

You could also strip some of the information out of the image. For instance, on that screen, the only thing that really needs to remain an image is the signature. The bars above and below that could be ripped out, and the numeric information could be sent as such and stored separately.