[Development] Moving JP2 imageformat from qt-solutions to qtimageformats

Rutledge Shawn Shawn.Rutledge at digia.com
Tue Nov 5 11:21:29 CET 2013

On 4 Nov 2013, at 10:51 PM, Mikkel Krautz wrote:

> Hello,
> I'm process of attempting to integrate support for the ICNS (OS X icon
> files) format into Qt as an icon engine.
> (https://codereview.qt-project.org/#change,60290)
> An optional, but desirable part of the ICNS format is support for
> JP2/JPEG2000 images. It's desirable because all variants of the icon
> greater than 128x128 are stored as JPEG2000 - so without JPEG2000
> support, the icon engine will only be able to render images at 128x128
> and below.
> It was pointed out during the review that a jp2 image format is
> available in the qt-solutions repository:
> https://github.com/qtproject/qt-solutions/tree/master/qtjp2imageformat
> and that it might make sense to move it into qtimageformats along with
> the icns icon engine itself.
> Does anyone see and/or have any problems with moving qtjp2imageformat
> to qtimageformats?

JPEG2000 apparently has some advantages, such as having multiple resolutions in one file and otherwise scaling better, as well as having a lossless compression option.  So it seems like a good format to use for icons.  I keep hoping that some day we will have the toolset to generate application icons from a single master file: .ico, .icns, various sizes for various Linux desktops, etc.  It should be enough to specify something like

ICON = myapp.jp2 (or svg)

in your .pro file and we should take care of the rest, consistently on all platforms.  (https://bugreports.qt-project.org/browse/QBS-73)  (Of course those who want to have separate icons for separate platforms would still be able to.)

I had thought SVG would be the best, but JPEG2000 would be a nice alternative for those who prefer a high-res raster representation.  Then maybe we should write a cross-platform icon editor which allows managing the various resolutions, if possible, or do the lower resolutions have to be generated from the high-res original?  If that were possible then maybe Apple would not have needed multiple sizes inside the .icns file at all.

BTW (unrelated) a fractal compresson format would be nice to have too; the patents from 1987 have expired now.  http://en.wikipedia.org/wiki/Fractal_compression

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