A case against JPG

[MegalosSkylaki]

Quote:

Originally Posted by Dark Blade

Just a quickie, the PNG format is basically an enhanced GIF format.

Doh!
What exactly is GIF and can I convert GIF to PNG?

Also, my new Panasonic Lumix camara takes pictures in RAW (cost $200).
So what are advantages/disadvantages of shooting in RAW?

DOOG''I expected no less than a GREAT article by OuT....tghat's why I let him out!

[xfxmonkey]

GIF is another format used for web pictures. PNG can also be used. but PNG is a higher quality format. you should not convert GIF to PNG it will do nothing but keep you image at the low quality but with a higher memory. you always have to down-vert your images TIFF, OR TIF (not sure how it's spelled) is the highest quality, PNG would be in the middle, and GIF and JPEG are on the bottom.

Shooting in Raw format is the highest quality you can get. it saves all the data for every color and shade and you can edit the different shades and colors in photoshop cs4 and or lightroom 2.4. but you can not view the raw in websites. you have to down-vert the quality... i would save a copy of the raw format to TIFF after adjusting the image, then save that as PNG OR JPEG (highest quality JPEG). I like to save lots of formats so i can use them for many occasions and for backups as well.. RAW takes up a lot of memory but it is the best

[herbstech]

Good analysis except you missed a few things:

1) Back in 2003, maybe they didnt have lossless JPEG but I am pretty sure they do now. Generally, lossless image compression is in the 2:1 to 3:1 range depending on the "randomness" of the image. So it seems reasonable that the 4:1 compression of the "best" JPG would have some artifacts.

2) A major concern about JPG is the speed of it. Remember many devices have to be able to handle JPGs quickly including low end digital cameras. An algorithm is needed to work quickly on those because I doubt people would want to wait 20 seconds while their camera compresses the image optimally.

3) Lossy compression such as standard JPEG was designed to throw away some detail that is "not very relevant". That is, in the original red block region you have, I would say 90+% of people wont notice that if it weren't zoomed like you did.

4) This original post also would have been more convincing had the original poster used a "real" image and not some made up one. Take a picture of some trees and "blow up" where they meet the sky.

5) Your statement to be careful saving to JPG because the damage it does cannot be undone is incorrect. Many image editors save the original copy in memory so any saving to JPG can be undone by reverting back to the original copy in memory and optionally blowing away the JPG file.