Comments on: Image resampling for LCD screens http://gidden.net/tom/2006/05/29/lcd-resampling/ Tue, 07 Feb 2012 05:55:56 +0000 hourly 1 http://wordpress.org/?v=3.3 By: Tom Gidden http://gidden.net/tom/2006/05/29/lcd-resampling/comment-page-1/#comment-43124 Tom Gidden Thu, 21 Jul 2011 06:14:03 +0000 http://gidden.net/tom/2006/05/29/lcd-resampling/#comment-43124 Rodrigo: well done! That's an excellent approach! Rodrigo: well done! That's an excellent approach!

]]> By: Rodrigo Cunha http://gidden.net/tom/2006/05/29/lcd-resampling/comment-page-1/#comment-43112 Rodrigo Cunha Thu, 21 Jul 2011 00:20:05 +0000 http://gidden.net/tom/2006/05/29/lcd-resampling/#comment-43112 Hi! I just reinvented this... in ImageMagick, using only already defined operations. If you want the command to do it, check my forum post: http://www.imagemagick.org/discourse-server/viewtopic.php?f=22&t=19120 The thing is, it's very easy to do already. No need for any new algorithm, just use normal image operations like resampling and matrices. I'm sure this can be done in OpenGL or DirectX rather quickly. Hi!

I just reinvented this... in ImageMagick, using only already defined operations.

If you want the command to do it, check my forum post:

http://www.imagemagick.org/discourse-server/viewtopic.php?f=22&t=19120

The thing is, it's very easy to do already. No need for any new algorithm, just use normal image operations like resampling and matrices.

I'm sure this can be done in OpenGL or DirectX rather quickly.

]]> By: Tobias http://gidden.net/tom/2006/05/29/lcd-resampling/comment-page-1/#comment-27318 Tobias Sun, 06 Sep 2009 19:42:47 +0000 http://gidden.net/tom/2006/05/29/lcd-resampling/#comment-27318 I am an LCD filtering maniac as well. And so I find this completely awesome. What do the options of lcdresample mean, though? -b does nothing and -n is used in the code for mode 0 but is not in the usage string. On the whole, I love the results! I found one other script that used Gimp, but gimp has horrible resampling and the filtering was naive. In your code vertical lines are fine. I think that in y-direction there could be a bit more antialias: http://www.alice-dsl.net/~towolf/img/lcdresample.png [ Imagemagick Mitchell filter for comparison: http://www.alice-dsl.net/~towolf/img/Mitchell.png ] Also I don’t understand the code properly. How does this relate to the 5-tap FIR filter that Freetype uses? http://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/src/base/ftlcdfil.c Are you using the same mechanisms? Can I convert the weights that FreeType uses (light_filter and default_filter) to the weights you include? I find FreeType more smooth in both x and y. Changing the strength -s does not make it much more smooth in the sense that lines become not only sharper (they do!) but also less jaggy. compare with this image: http://www.alice-dsl.net/~towolf/cairo/displaytext-fir5.png But your tool is already very useful. Did you submit this upstream? To Imagemagick of to Cairo? I would love to see Cairo support this in it’s renderer. I am an LCD filtering maniac as well. And so I find this completely awesome.
What do the options of lcdresample mean, though? -b does nothing and -n is used in the code for mode 0 but is not in the usage string.

On the whole, I love the results! I found one other script that used Gimp, but gimp has horrible resampling and the filtering was naive.
In your code vertical lines are fine. I think that in y-direction there could be a bit more antialias:
http://www.alice-dsl.net/~towolf/img/lcdresample.png

[ Imagemagick Mitchell filter for comparison:
http://www.alice-dsl.net/~towolf/img/Mitchell.png ]

Also I don’t understand the code properly. How does this relate to the 5-tap FIR filter that Freetype uses?
http://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/src/base/ftlcdfil.c
Are you using the same mechanisms? Can I convert the weights that FreeType uses (light_filter and default_filter) to the weights you include?

I find FreeType more smooth in both x and y. Changing the strength -s does not make it much more smooth in the sense that lines become not only sharper (they do!) but also less jaggy.
compare with this image: http://www.alice-dsl.net/~towolf/cairo/displaytext-fir5.png

But your tool is already very useful. Did you submit this upstream? To Imagemagick of to Cairo? I would love to see Cairo support this in it’s renderer.

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