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File Formats: Why we use certain ones and not others
Posted: Sat Dec 20, 2008 3:24 am
by Danny420Dale
Repost from Stardestroyer.net.
Einhander Sn0m4n wrote:Sample image is a 820x2250 (aka Very Large!) schematic of a thermonuclear railgun projectile, which, in the BMP file format, weighs 5.28MB on disk. This image was chosen to be representative of the output of an advanced MSPaint user in making a starship design. There are gradients and subtle color variations present within the schematic which are not present in the default Paint palette, as you can see. Most ship designers stick to the default Paint palette, which I suspect would give GIF an edge in this test.
The purpose of this experiment is to show which is the best file format to save a schematic of this type through a combination of file size, fidelity in rendition, and ease of data repair.
Schematic saved in MSPaint; default compression JPEG: 94kb; data damage apparent in form of smeared or blurry lines, edges, and fonts.
Schematic saved in Irfanview; default compression (85%) JPEG: 94kb; data damage slightly more visible.
Schematic saved in MSPaint; default compression GIF: 63kb; MASSIVE DAMAGE extremely obvious in the form of color dithering over very nearly the entirety of the schematic! File size is small for an image this size.
Schematic saved in Irfanview; default compression (85%) GIF: 139kb :wtf: Data damage in form of color inaccuracy present, readily seen in the gray gradients. Large file size!
Schematic saved in Irfanview, default compression factor (7) PNG: 26kb! No data damage visible at all due to lossless format. File size is clearly the smallest by a factor of 2.6 to its nearest GIF competition and nearly 4 against the JPEGs.
Posted: Sat Dec 20, 2008 3:31 am
by Aralonia
Go on, post a .PNG file of a photograph
Posted: Sat Dec 20, 2008 3:39 am
by Danny420Dale
For photos, yes, the JPEG file format is optimized. This MSPaint weapon schematic is a different case entirely, being neatly at the other end of the range of scenarios with its hard edges and relatively simple coloring.
However, a BSF screenshot can be done with a PNG acceptably because it most likely doesn't have nineteen billion colors like a photo usually does, and the antialiasing isn't severe enough to cause color multiplication over every last tiny detail like a photo. I'd imagine a BSF screenie falls in between the two extreme scenarios but closer to the MSPainted schematic. This is why JPEG causes significant, irreversible, and highly visible damage for a gain in filesize efficiency small enough to be debatable.
Posted: Sat Dec 20, 2008 4:27 pm
by Master Chief
Since Danny already has given us a perfectly decent explanation as to which file format to use, I'll just cut this short:
Use .png files for screenshotting, keep away from ImageShack, and allow us to preserve the sanities we have been attempting to preserve for a really long time already.
Posted: Sun Dec 21, 2008 2:17 am
by Danny420Dale
Master Chief wrote:keep away from ImageShack
Yep.
Posted: Sun Dec 21, 2008 2:22 am
by Smut
Photobucket is so much easier to use, and it posts full size images.
Posted: Sun Dec 21, 2008 2:26 am
by Swamp Fox
Photobucket is so much easier to use, and it posts full size images.
Imageshack posts full-sized images, it's just frustrating to use and rather slow.
Posted: Sun Dec 21, 2008 7:58 am
by Hege
Swamp Fox wrote:Photobucket is so much easier to use, and it posts full size images.
Imageshack posts full-sized images, it's just frustrating to use and rather slow.
The thing with imageshack is that people don't usualy see the hidden direct link option on the bottom which makes the image viewing easier for others.
I think I should start listing some image hosting sites at some point and make little guides using them.
Posted: Sun Dec 21, 2008 10:12 am
by Slayer0019
I wrote: Irfanview can open every file type known to man, and several known to dolphin. Paint.NET is what happened when Photoshop knocked up MS Paint and sent the baby to live with GIMP.
