On Sat, 07 Jul 2007 18:58:28 +0200, Guillermo Espertino  

> We, the users, tend to assume things based on the information we get on  
> screen.
.. or not on the screen, like percentages. ;)

>  It's very clear that Photoshop doesn't use the IJG scale, but it  
> should. Users who came from PS are used to that incorrect scale, and  
> find this difference.
> I think it should be documented in the Gimp Manual and FAQs. It's not a  
> minor issue.

The key point to realise is that gimp<>ps ; linux<>windows. It's well  
documented that gimp does not aim to be free PhotoShop. You pay your money  
(or not) and you make you choice.

Just because some software has established a dominant position in a  
particular market does not mean everyone has to clone it. Especially when  
no even competing in that market.

Somethings are better , some worse, it's DIFFERENT. Those that cant handle  
that had better pay for PS.

> I repeat: I just open them from the camera and they look great (Nikon  
> Coolpix 800), adjust levels, curves and >color (they still look great),  
> scale them down, and save them using CTRL+S. When I re-open them they  
> are >distorted. I'm not talking about repetitive openings and saves.

Until you reopen the image you dont see the changes made by the jpeg  
compression. That's normal but I dont get your point here.

Are you saying gimp is badly implementing the save and you can get better  
results doing the same thing with PS?
Try doing you colour operations , saving as non lossy png then resave the  
same image with gimp and ps as jpeg and compare.

Are you saying gimp default quality/compression setting is not well chosen?

You dont seem to have grasped one fundemental point. It's not "I just open  
them from my camera and they look great" it's "my camera destroys some of  
the essential data by saving them internally as jpeg before I even get  
it". When you do further (and please note _major_ ) changes to that data  
and resave as jpeg you are getting hit by the fundemental weakness of DCT  
encoding, you lose quality. If you dont like this use gimp's xcf and/or  
png to maintain all the data your camera gives you.

If you are able to adjust your camera to a better jpeg ratio you will lose  
less quality after processing and may still get good results with jpeg.


>  Thanks everybody for your explainations!

you're welcome!
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