I’ve written a little app to downsize and convert images, for bandwidth issues, and I’m running into something strange. When saving as png, if the image is downsized, the resulting file is larger than if I merely convert to png and leave the resolution large.
I’m using GDI+ to do the resizing / converting, via the System.Drawing namespace.
At first I thought it was a PixelFormat issue, but I’ve ruled that out by implicitly specifying to use the incoming pixel format.
Can anyone tell me why this image has a larger file size than this one, even though the second has three times as many pixels? They’re both 24 bits-per-pixel pngs.
It looks like anti-aliasing has bit you. Because the image is no longer straight black/white, it is harder to compress efficiently.