How do I turn screenshots for my computer into acceptable pictures for instructables?

I have an instructable on software to design better curved reflectors for solar cookers (among other things). Anyways, I put in screenshots of how I use the software and of my results tabulated in a html page with the pictures of different reflectors and how good they are in tables. The screenshots are actually fine but when i upload them they turn brutal. How can i keep the quality of the screenshot after uploading. This is really important for this particular instructable. The screenshots show that for a 1 or 2 hour unattended cooktime, there are several curves that are significantly better than a parabolic dish. But they do not show anything much after upload! I have the most recent one below. Brian

Picture of How do I turn screenshots for my computer into acceptable pictures for instructables?
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kelseymh8 years ago
Don't save as JPG. Save as either GIF or PNG. The JPEG compression algorithm is built around the assumption that the image consists of a continuous gradation of color, with intermittent edges (i.e., a photograph. The GIF and PNG compression algorithms are built around the assumption of "blocks" of single colors, such as line drawings. Your image above is much better suited for GIF or PNG than for JPEG.
agreed. I suggest PNG in particular, but would resize to the instructables big picture posting size, and save the file since they say above it will be converted anyway. That way you won't get the lossy qualities of resizing, only of the conversion itself. It's also my understanding it's also possible to see pictures at the original size, though I've never actually had need to try this... but if that's the case, you may re-consider resizing at all.
110100101108 years ago
insts converts images to jpeg jpeg sucks (except for photos where its not very noticable)
lemonie8 years ago
(other comments noted) I used 16 colour bitmaps for this one (excepting the XP window), because they're small and sharp. It's worth thinking about colour depth / file size for images like this and the one you posted.

NachoMahma8 years ago
. I think part of the problem is that Ibles will resize some pictures when needed. Resizing frequently introduces artifacts. I haven't researched this, just the way it "feels" to me. If this is true, try to find out what sizes Robot considers standard and make sure your pics are one of those sizes. . . kelseymh makes a good point about JPEG/GIF/PNG - JPEG frequently doesn't do well with non-photo images.
n8man8 years ago
Hmmm, My screen shots seem to turn out fine, maybe they get smaller when put on topics and such. Try going to the picture source page and changing the capital letters at the back to ORIGINAL.
n8man n8man8 years ago
Make that LARGE, it looks very good on large and says that ORIGINAL does not exist.
caitlinsdad8 years ago
Have you tried to see if there is a difference with saving the final image as a jpeg instead of .png to upload? I don't know if the file format is not handled well. Maybe get a higher resolution screenshot if possible.