Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
yush125
Posts: 4 Joined: 2013-05-02T04:21:49-07:00
Authentication code: 6789
Post
by yush125 » 2013-05-02T04:31:39-07:00
Here is document and sample about redusing color RGBA32bit color to RGBA8bit with high quality.
http://www.webtech.co.jp/imesta/psp/f_alpha_blend.html
Here is sample picture.
And this is my command and result picture "orijinal_after.png"
Code: Select all
convert "orijinal.png" -ordered-dither o8x8,8,8,8 "orijinal_after.png"
Result of 32bit to 8bit color with using IM.
It has bit more noisy than Optpix imesta's one.
If you know more better option , tell me about that.
fmw42
Posts: 25562 Joined: 2007-07-02T17:14:51-07:00
Authentication code: 1152
Location: Sunnyvale, California, USA
Post
by fmw42 » 2013-05-02T09:20:23-07:00
You are dithering which will add the dither pattern. I suspect that is not what you want to do.
try
convert image.png PNG8:result.png
glennrp
Posts: 1147 Joined: 2006-04-01T08:16:32-07:00
Location: Maryland 39.26.30N 76.16.01W
Post
by glennrp » 2013-05-02T12:12:30-07:00
fmw42 wrote: You are dithering which will add the dither pattern. I suspect that is not what you want to do.
try
convert image.png PNG8:result.png
PNG8 does quick-and-dirty color reduction and will produce severe banding.
Code: Select all
convert image.png -colors 255 result.png
will do better. Or, if you want a 1-bit alpha channel, use png8: after reducing
the colors:
Code: Select all
convert image.png -colors 255 png8:result.png
anthony
Posts: 8883 Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia
Post
by anthony » 2013-05-02T17:52:29-07:00
The ordered dither only provides a uniform colormap. As a consequence no all colors in that map is being used for that image.
You can increase the color counts until you get about 255 colors in the reulting image.
An example of doing this is in Video to GIF animation
http://www.imagemagick.org/Usage/video/#gif
Look for "Higher Quality Ordered Dithered Video"
yush125
Posts: 4 Joined: 2013-05-02T04:21:49-07:00
Authentication code: 6789
Post
by yush125 » 2013-05-04T02:11:20-07:00
Hi,everyone.
fmw42,glennrp,anthony Thank you for answering.
That's a very helpful for me.
And I did as following your advice.
Here is result.It's quite better than my first.Almost I satisfied with that.
Thank you very much.
yush125