On Thu, 12 Jul 2007 23:29:01 +0200, gg@xxxxxxxxxxx wrote: > If there is an image specific value you do not need a default. > "overriding" a default with an image-specified value is a contradiction. This reminds me about something that should be clarified... For all these parameters that affect how an image is saved, where do these various values and defaults come from, and how to name them? I propose the following terms (feel free to propose something else if you have better ideas): "default", "original" and "current" values. This is a slightly expanded version of the comment #14 that I added to bug #63610 in 2003; in that comment I forgot the "original" setting. 1) The "default" setting is the one that is hardcoded or configurable in GIMP or in one of its plug-ins. Sometimes the "default" value can be empty or not set. Some examples: a default image comment can be configured in the Preferences, the JPEG plug-in uses a default quality setting of 85, GIF does not interlace the file by default, etc. The "default" setting applies to all images. 2) The "original" setting is the one that is found (or not) when an image is loaded from disk. For example, an image file may include a user comment and this comment will be preserved when the file is saved later. The "original" setting only applies to that specific image. 3) The "current" setting is whatever is currently associated with one specific image. Once it is set (coming from the "default" or "original" setting), it will always be used whenever this image is saved. It can usually be changed by the user in the dialog window of the file plug-in. In theory, these parameters should work like this: all new images or images loaded from disk get the "default" setting except if some files have an "original" setting, which is then used instead of the default one. This then becomes the "current" setting, which is associated with that image every time it is saved. In practice, there are several exceptions due to implementation details or leftovers from the past. For example, the "current" setting may not actually exist until the file is saved (it only exists once the save plug-in creates it). But there is a bigger problem that I mentioned in bug #63610. There is a confusing historical feature that introduces another source of settings for some parameters: 4) The "session" setting is a side-effect of the fact that file plug-ins currently behave like other plug-ins (filters). This is a value that is set the first time you save a file in a specific format and that will affect all other images that you save during that session (until you quit GIMP). This behavior is appropriate for filters but is confusing and dangerous for file plug-ins. The problem with "session" settings is that something that is changed when saving one image can trigger unexpected changes in all other images. For example, you use Save As to save an image using lower quality settings for testing, but you do not see that from then on, all other images that you save (normal Save) in the same format will also use that lower quality instead of using the default value. IMNSHO, the right way to fix bug #63610 is to provide an easy way for all file plug-ins to save and reload one or more sets of "default" values and then forbid all file plug-ins from using "session" settings (save_args or save_vals or whatever the array of saved GimpParamDef is called in each plug-in). In fact, removing the usage of session settings could already be done right now in all file plug-ins, even before having a nice library for file plug-ins that would provide a unified way to save and load default values. This would solve one of the problems that has started this long thread about the JPEG quality factor: saving one image in low quality will not cause other unrelated images to be also saved in low quality. The other improvement that can be implemented without waiting is to read or compute the "original" quality from JPEG files and to use it if and only if it is better than the "default" quality. I am working on a simple extension of the nice patch that Tor provided a few days ago. -Raphael _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
