GNOME Bugzilla – Bug 508873
gthumb cannot scale up images
Last modified: 2008-01-16 21:15:12 UTC
I'm using latest version gthumb 2.10.8 in Xubuntu 7.10 on i386. Gthumb can scale images down but it cannot make them bigger....dimensions remain same but only file size increases. This is using the scale option under tools for single or batch resizes. I use jpeg images of normal (divisible by 8) dimensions. I can see no workaround other than using different application for resizing/scaling.
Question : why do you want to make them bigger ? If you do so, big pixel will appear : what use ? This is not a bug, but mis-usage of the software. Maybe scale tool should prevent that (warning ?). Severity should be changed to minor, Status to NOTABUG. Cheers, Matthias
(In reply to comment #1) > Question : why do you want to make them bigger ? > If you do so, big pixel will appear : what use ? > > This is not a bug, but mis-usage of the software. > Maybe scale tool should prevent that (warning ?). > Severity should be changed to minor, Status to NOTABUG. > > Cheers, > Matthias > It's normal to upscale or downscale images as preparation for printing, particularly when the printshop requires images at 300dpi*. This is the standard requirement for professional/high end photo printing. You can see that all "serious" image editors such as Gimp and Photoshop include this feature. It is also found in similar applications/applications which target similar useage to gthumb, such as phatch or XnView in Linux and IrfanView in Windows. It can be considered an essential element of any tool which includes the ability to batch process images, and is really the only serious deficiency in gthumb when used a batch tool. If you do actually consider upscaling to be a mis-use may I suggest either have a look at similar tools and in that light reconsider this assertion or change the gui so it is clear that it is not possible. At the moment the option in gthumb is clearly there....but it fails to work. *example: a camera might produce images which at 300 dpi are perhaps 9"x6" or similar. The photographer wants to produce prints of 12"x8"(standard size in UK/USA). The print shop requires the images to be @300dpi....the photographer then uses a batch process tool to scale up the images, usually the rescaling is accomplished with a bicubic algorithm to preserve as much image quality as possible. Typically there is no noticeable loss of quality (big pixel does not appear!) and the photographer gets his/her prints at 12"x8". Again, this is a standard feature of every good photo editor and most good general photo tools similar to gthumb and is a major omission in an otherwise 1st class and well considered feature set.
This is supposed to work. Image>Resize works as expected, it's just the batch tool that is broken. I think something is broken in the function scale_keepping_ratio. - Mike
It should be fixed in svn now. The fix should appear in 2.10.9 and later. Compile from svn if it is bothering you right now :-) - Mike
that's great, thanks
(In reply to comment #2) > It's normal to upscale or downscale images as preparation for printing, > [...] Downscale I can understand. Upscale, yes to a certain extend... At some point the upscaling algorithm will reach its limits. Well seems like Mike fixed the bug. So everyone is happy now. Thanks ! Matthias
yes it works, very nice :-)