Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On 05/05/2011 01:06 AM, Sebastian Pipping wrote: I stumbled upon the article Gamma error in picture scaling http://www.4p8.com/eric.brasseur/gamma.html#Use_a_correct_software recently. I was actually pointed to it be some tool applying the proper algortihm. I think it was command line. In the meantime a person called Jure kindly pointed me to media-gfx/imageworsener now, which is what I initially was looking for. Best, Sebastian
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On 05/06/2011 05:06 AM, Kfir Lavi wrote: What about using gimp in scripting mode? I've been working on a pygimp-based plugin for the GIMP yesterday. It's a bit slow but it does the job, and comes with a simple GUI [1]. After running # sudo layman -a betagarden # sudo emerge -av media-plugins/gimp-imagescaler you should find an item Scale Image with correct Gamma... at the bottom of the Image menu as seen on [2]. The sources are up at [3]. Best, Sebastian [1] https://blog.hartwork.org/__images/imagescalerplugin-dialog-332x395.png [2] https://blog.hartwork.org/__images/imagescalerplugin-menu-394x449.png [3] http://git.goodpoint.de/?p=imagescaler.git;a=summary
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On 05/06/2011 12:05 AM, Paul Hartman wrote: Doesn't Netpbm satisfy your criteria? It's the very first program on the list of good software in that web page. I have a had a closer look at netpbm's pamscale now. pamscale doesn't support PNG input out of the box: pamscale: bad magic number 0x8950 - not a PAM, PPM, PGM, or PBM file So to let pamscale operate on my PNG it seems I would need to run this # pngtopam in.png in.pam # pamscale [..] in.pam out.pam # pamtopnm out.pam out.pnm # pnmtopng out.pnm out.png I haven't checked yet if that preserves transparency. While there is a tool pamrgbatopng shipped with netpbm it didn't like my out.pam produced above: pamrgbatopng: PAM must have depth at least 4 (red, green, blue, alpha). This one has depth 3 Interestingly netpbm tools point to a respective man page when run with --help, which points to a man-like website with the real content. So it seems without internet the tool is effectively unusable. Great. I'm also not sure if I really want to add 300 binary files from a single package: # equery f media-libs/netpbm | grep '^/usr/bin' | wc -l 331 Best, Sebastian
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On 05/06/2011 05:06 AM, Kfir Lavi wrote: What about using gimp in scripting mode? There seems to be options on Scheme, Python and Lua (Gimp plug-in gluas). Eric Brasseur (the author of the article on Gamma) offers a Lua script for gluas, which is why I wrote an ebuild for gluas now: # sudo layman -a betagarden # sudo emerge -av media-plugins/gimp-gluas The script throws an error in my setup though, that I am not able to fix myself quickly. I have just contacted Eric about it. I have not looked into the Scheme and Python options yet. Best, Sebastian
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On Wed, May 4, 2011 at 6:06 PM, Sebastian Pipping sp...@gentoo.org wrote: Hello! I stumbled upon the article Gamma error in picture scaling http://www.4p8.com/eric.brasseur/gamma.html#Use_a_correct_software recently. I was actually pointed to it be some tool applying the proper algortihm. I think it was command line. Especially as I don't trust ImageMagick with files that matter I would love to find (or re-find) a command line tool that properly handles Gamma when resizing images. Needs be free software. Anyone? ImageMagick works. I downloaded the Dalai Lama photo from that page and converted it by doing: convert -colorspace sRGB gamma_dalai_lama_gray.jpg -scale 50%% -set colorspace sRGB gamma_dalai_lama_gray50.png And the resulting image is correct.
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On Thu, May 5, 2011 at 12:48 PM, Paul Hartman paul.hartman+gen...@gmail.com wrote: On Wed, May 4, 2011 at 6:06 PM, Sebastian Pipping sp...@gentoo.org wrote: Hello! I stumbled upon the article Gamma error in picture scaling http://www.4p8.com/eric.brasseur/gamma.html#Use_a_correct_software recently. I was actually pointed to it be some tool applying the proper algortihm. I think it was command line. Especially as I don't trust ImageMagick with files that matter I would love to find (or re-find) a command line tool that properly handles Gamma when resizing images. Needs be free software. Anyone? ImageMagick works. I downloaded the Dalai Lama photo from that page and converted it by doing: convert -colorspace sRGB gamma_dalai_lama_gray.jpg -scale 50%% -set colorspace sRGB gamma_dalai_lama_gray50.png And the resulting image is correct. I will add the disclaimer that it *appears* correct to me. It is not a solid grey image like the bad examples on that page. I don't fully understand what that page is talking about and most of it was a whooosh over my head. :)
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On 05/05/2011 07:48 PM, Paul Hartman wrote: Especially as I don't trust ImageMagick with files that matter I would love to find (or re-find) a command line tool that properly handles Gamma when resizing images. Needs be free software. Anyone? ImageMagick works. I downloaded the Dalai Lama photo from that page and converted it by doing: convert -colorspace sRGB gamma_dalai_lama_gray.jpg -scale 50%% -set colorspace sRGB gamma_dalai_lama_gray50.png And the resulting image is correct. As I said, I do not trust ImageMagick with quality. I am looking for a different tool. Sebastian
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On Thu, May 5, 2011 at 4:25 PM, Sebastian Pipping sp...@gentoo.org wrote: On 05/05/2011 07:48 PM, Paul Hartman wrote: Especially as I don't trust ImageMagick with files that matter I would love to find (or re-find) a command line tool that properly handles Gamma when resizing images. Needs be free software. Anyone? ImageMagick works. I downloaded the Dalai Lama photo from that page and converted it by doing: convert -colorspace sRGB gamma_dalai_lama_gray.jpg -scale 50%% -set colorspace sRGB gamma_dalai_lama_gray50.png And the resulting image is correct. As I said, I do not trust ImageMagick with quality. I am looking for a different tool. Doesn't Netpbm satisfy your criteria? It's the very first program on the list of good software in that web page.
Re: [gentoo-user] Cmdline image resizer understanding gamma ?
On Fri, May 6, 2011 at 12:25 AM, Sebastian Pipping sp...@gentoo.org wrote: On 05/05/2011 07:48 PM, Paul Hartman wrote: Especially as I don't trust ImageMagick with files that matter I would love to find (or re-find) a command line tool that properly handles Gamma when resizing images. Needs be free software. Anyone? ImageMagick works. I downloaded the Dalai Lama photo from that page and converted it by doing: convert -colorspace sRGB gamma_dalai_lama_gray.jpg -scale 50%% -set colorspace sRGB gamma_dalai_lama_gray50.png And the resulting image is correct. As I said, I do not trust ImageMagick with quality. I am looking for a different tool. Sebastian What about using gimp in scripting mode? Kfir
[gentoo-user] Cmdline image resizer understanding gamma ?
Hello! I stumbled upon the article Gamma error in picture scaling http://www.4p8.com/eric.brasseur/gamma.html#Use_a_correct_software recently. I was actually pointed to it be some tool applying the proper algortihm. I think it was command line. Especially as I don't trust ImageMagick with files that matter I would love to find (or re-find) a command line tool that properly handles Gamma when resizing images. Needs be free software. Anyone? Thanks, Sebastian
