> On Thu, 30 Aug 2007 11:07:40 +0200, Raphaël Quinet <raphael at gimp.org> > wrote: > On Thu, 30 Aug 2007 00:57:44 +0200, gg at catking.net wrote:>> Gimp should not decide what is "better" because it cannot know what is>> required so cannot make that choice.>>>> This sort of "surprise" behaviour is precisely the kind of thing I was>> warning against in making covert changes to user data.>> I think that you are trying to shoot the wrong target. The main> problem that I described in my previous message is not the fact that> GIMP tries to preserve the quality of the original image or decide> what is "better". The problem is that some changes that you make when> saving one file are propagated to all other files that you save later.> The recent updates to the JPEG plug-in make this problem more obvious,> but it also affects all other file plug-ins.>> Before jumping to conclusions about where the problem comes from, please> try the following exercise:> - Load or create a GIF animation (2-3 layers should be enough).> - Save it as A.gif and let's pretend that you don't like the speed at> which that animation runs so you set the delay to 333ms and check> the box "Use delay entered above for all frames".> - Close that image.> - Open or create a new, totally unrelated GIF animation.> - Save that image as B.gif. Although you probably wanted to keep its> settings or at least save it with the default values, you see that> "Use delay entered above for all frames" is now checked. The> settings from an unrelated image that is now closed are used for> saving your new image. If you do not want to destroy the timing of> your animation, you have to pay attention and uncheck that box> before you save the file.>> Does it make sense that two unrelated images influence each other?>> But things are even more confusing if you keep some images open. Try> the following exercise, with PNG this time:> - Load or create a new image.> - Save it as A.png but set its compression level to 0 because you want> to waste some disk space and disable all other options because you> do not want to save the image comment, creation date, etc.> - Keep A.png open and load or create another image.> - Save the second image as B.png. Although you probably wanted to use> your default settings (which can be customized with the buttons> "Load/Save defaults"), you see that the same parameters as A.png are> now used when saving this image. You do not like this, so you set> the compression level back to 9 (you can also check or uncheck some> of the other boxes) and save the image.> - With both A.png and B.png still open, load or create a third image.> - Save that image as C.png. Now you see that C.png inherited the> settings from B.png, the last image that was saved.> - Make some small changes to A.png and save it again using a new name> such as D.png. By now, maybe you expect that saving D.png would use> the same settings as C.png, the last image that was saved? But no,> this time you see that D.png keeps the settigns from A.png because> it was still open.> - Now if you make some changes to B.png and give it a new name E.png,> then that file will use the settings from B.png. But if you had> closed and re-opened B.png, then you would see that E.png is saved> with the parameters from D.png, not B.png. Are you confused yet?>> If you work on two files in parallel (A.png and B.png) and save them> alternatively as your work progresses, then any new file that you open> and save will inherit the settings from A.png or B.png, depending on> which one was saved last.>> And if you are still convinced that all of this makes sense, try to> play with some settings that are enabled or disabled depending on the> contents of the original image. For example, if the original PNG> image has transparency (alpha channel), then you will be able to check> or uncheck the box "Save color values from transparent pixels". This> setting may be propagated to other PNG images that also have an alpha> channel. But if you load a PNG image without alpha channel, then this> option will not be available. After saving that last file, can you> correctly guess if that box will be automatically checked or not when> you load another PNG image with transparency and then try to save it?>> I consider the current situation to be broken for all file plug-ins.> Instead of re-using the settings from whatever image was saved> recently, each image should keep its own settings and should not be> influenced by what you do with the other images. The save settings> should come from the original image or from the user defaults if the> image has never been saved yet. It should of course be possible for> the user to customize these defaults (currently, this can only be done> for JPEG and PNG, but the old bug #63610 is about extending this to> other plug-ins).>> I hope that you are convinced that something is wrong with the> behavior of the file plug-ins.>> Now, regarding the JPEG plug-in, I see two ways forward:>> 1) Do not re-use the values from previous (unrelated) invocations of> the plug-in. This ensures that each file keeps its own settings,> as described above. The same fix can also be applied to the PNG> plug-in because it uses similar parasites for saving image settings> and it also has the "Load/Save defaults" buttons. But other> plug-ins will still have the wrong behavior because it is too late> to fix all of them before 2.4.>> 2) Instead of trying to fix the plug-ins for 2.4, make sure that they> are all broken in the same way. This would mean that the JPEG> plug-in in 2.4 will not try to use the quality settings from the> original image even if they are better than the defaults. We would> go back to the previous behavior and postpone the real fix> explained above until the next development cycle. Those who> complained that GIMP was "destroying" their images by saving them> at a lower quality than expected will just have to wait for 2.6.>> I don't care about which way we go. Both of them have good and bad> sides and both of them will leave some users frustrated or confused.>> -Raphaël> _________________ May be we need switch (radio or combo):- Use default settings- Use previous settings- Use settings from the original image_______________________________________________Gimp-developer mailing listGimp-developer@xxxxxxxxxxxxxxxxxxxxxxxxxxx://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
