[PUSHED] Re: [PUSHED] Re: [PATCH] fdo#46378: Poor Resampling Image quality

[Jan Holesovsky]

Hi Tomaž,

On 2012-06-06 at 23:22 +0200, Tomaž Vajngerl wrote:

> > Great stuff - I have pushed your patch, and also my patches to default
> > to Lanczos filter.  Can you please add an example of "before" and
> > "after" where the advantages of the Lanzcos filter are nicely visible to
> > the Release Notes (http://wiki.documentfoundation.org/ReleaseNotes/3.6)?
> Done.

Great picture, thanks a lot!

> > Adding the QA list to the CC: - thanks to Tomaz, we have changed the
> > default of the image resize operations to a new scaling operation.
> > Please be careful about bugs that involve scaling of images, quality of
> > eg. PDF output, or speed of such operations.
> Regarding bugs.. I have found a problem with creation of Bitmaps in
> ImplScaleLanczos. I have fixed so the Bitmaps are created in the same
> way as in ImplScaleInterpolate - the patch is attached. This problem
> is visible if you go into impress and set the background of a slide to
> a bitmap which is tiled. I have not found any reports in bugzilla
> about this yet.

Pushed :-)

Actually - can you ask for push access?  Your patches are consistent,
look good, and you know what you are doing, so would be great if you
could push them yourself.  Of course in case of doubts, you can still
ask for a review on the ML first.

http://wiki.documentfoundation.org/Development/NewAccount

Please CC: michael.meeks at novell.com on the bug you create.

> > Tomaz - what interests you next? :-)  You've already outlined some ideas
> > regarding the filters, correct?
> I am working now to on blur/soften filter which uses
> ImplHorizontalConvolution and ImplVerticalConvolution - which are also
> used in Lanczos resampling. I have this already working with a
> parameterized blur radius. Currently the soften filter only uses a
> fixed 3x3 convolution matrix with 2D convolution algorithm. My
> solution should be faster and more flexible than the current one. I
> still need to add a dialog to select the blur radius which I will do
> in step 2.
> 
> Other ideas I have is to add "reduce image resolution" function
> directly to bitmap so a user could change the image resolution not
> only in PDF export but in general. When a user applies a filter, the
> image is changed and saved as a new PNG image into the document. So to
> create something like this should not be hard.
> 
> In a long run I want to improve the quality of images in export but I
> think this is a problem of whole page rendering and not so simple to
> solve.

That sounds great, should you need any code pointers, I'll be glad to
help.

All the best,
Kendy