Re: [Gimp-developer] improving image scale: reduction

2007-06-11 Thread g4
On Sun, 10 Jun 2007 23:41:01 +0200, Sven Neumann [EMAIL PROTECTED] wrote: Hi, On Sun, 2007-06-10 at 14:42 +0200, [EMAIL PROTECTED] wrote: For GIMP 2.6, we will need high-quality and optimised scaling algorithms implemented as GEGL operators. Perhaps it would be a good idea to write

Re: [Gimp-developer] improving image scale: reduction

2007-06-11 Thread Guillermo Espertino
From the user perspective, the downscaling quality is very important. More if you consider using GIMP for web graphics production, where downscaling is one of the most frequent operations. It would be nice if this problem is addressed before 2.4 I understand the stability risk being so close to

Re: [Gimp-developer] improving image scale: reduction

2007-06-11 Thread Sven Neumann
Hi, On Mon, 2007-06-11 at 13:04 -0300, Guillermo Espertino wrote: I wouldn't say it's a critic item, but the current algorithms are right now quite sub-standard. I might be wrong but I think the current algorithms are basically the same as the ones used in GIMP 2.2. So there's really no

Re: [Gimp-developer] improving image scale: reduction

2007-06-10 Thread g4
On Sun, 10 Jun 2007 05:53:57 +0200, [EMAIL PROTECTED] wrote: I think cubic (catmull-rom as per scale up) should give better results. It may be necessary to decide a policy for reductions greater than 4:1 to avoid ignoring some data points. As I suspected the catmull-rom spline works better

Re: [Gimp-developer] improving image scale: reduction

2007-06-10 Thread Sven Neumann
Hi, On Sun, 2007-06-10 at 05:53 +0200, [EMAIL PROTECTED] wrote: in result of some comments in #166130 I have been looking at image scaling in scale-funcs.c It seems the needs of scale down are quite different from the interpolation of scaling up so there are certain compromises in

Re: [Gimp-developer] improving image scale: reduction

2007-06-10 Thread g4
On Sun, 10 Jun 2007 13:12:02 +0200, Sven Neumann [EMAIL PROTECTED] wrote: Hi, On Sun, 2007-06-10 at 05:53 +0200, [EMAIL PROTECTED] wrote: in result of some comments in #166130 I have been looking at image scaling in scale-funcs.c It seems the needs of scale down are quite different

Re: [Gimp-developer] improving image scale: reduction

2007-06-10 Thread Sven Neumann
Hi, On Sun, 2007-06-10 at 14:42 +0200, [EMAIL PROTECTED] wrote: For GIMP 2.6, we will need high-quality and optimised scaling algorithms implemented as GEGL operators. Perhaps it would be a good idea to write such operators now so that we can start to use them when we port the core to

[Gimp-developer] improving image scale: reduction

2007-06-09 Thread g4
Hi, in result of some comments in #166130 I have been looking at image scaling in scale-funcs.c It seems the needs of scale down are quite different from the interpolation of scaling up so there are certain compromises in using the same lin/cubic/lanczos list of options. currently linear