Search found 26 matches

by elmimmo
2019-02-01T02:56:26-07:00
Forum: Bugs
Topic: Inefficient compression of CMYK images
Replies: 5
Views: 5120

Re: Inefficient compression of CMYK images

The reason for the inefficient compression ratio of CMYK images has been found and explained in the comments of the bug report at tiffinfo , and it is indeed something that should be fixed in ImageMagik, not tiffinfo. As a matter of fact, the issue, reason and potential solution was already hinted a...
by elmimmo
2018-04-26T01:01:16-07:00
Forum: Bugs
Topic: Inefficient compression of CMYK images
Replies: 5
Views: 5120

Re: Inefficient compression of CMYK images

contact the libtiff developers. Do you know how? The contact info for bug reports at libtiff.org refers to a mailing list whose interface returns 404 and a bugtracker whose domain does not even resolve. UPDATE: Duh… Apparently libtiff.org is not the official site for libtiff anymore. Wikipedia stat...
by elmimmo
2018-04-25T01:17:49-07:00
Forum: Bugs
Topic: Inefficient compression of CMYK images
Replies: 5
Views: 5120

Inefficient compression of CMYK images

ImageMagick does not seem to efficiently compress TIFF CMYK images. Photoshop manages to Zip/LZW compress the same images to about 1/10 the size of what ImageMagick outputs. If I create an LZW-compressed RGB TIFF with ImageMagick of a full rainbow gradient: convert -size 8500x5000 \ -define gradient...
by elmimmo
2018-04-17T08:44:46-07:00
Forum: Users
Topic: Not like in the docs: Gradients in other Colorspaces
Replies: 2
Views: 1502

Re: Not like in the docs: Gradients in other Colorspaces

`-colorspace sRGB` instead of `-colorspace RGB` did indeed fix it. Thanks!
by elmimmo
2018-04-17T08:42:05-07:00
Forum: Users
Topic: Keep/discard alfa depending on opacity
Replies: 2
Views: 1458

Re: Keep/discard alfa depending on opacity

I found that I can query if the composite PSD "is image fully-opaque?" with

Code: Select all

identify -format %[opaque] ${PSD}[0]
by elmimmo
2018-04-17T08:32:51-07:00
Forum: Users
Topic: Keep/discard alfa depending on opacity
Replies: 2
Views: 1458

Keep/discard alfa depending on opacity

I want to batch convert multiple PSD to a TIFF files without layers. If I am not mistaken, I can just grab the composite version of the PSD by appending [0] to its filename, but then, regarding the alpha, is there a way to programmatically keep it or discard it depending on whether there actually ex...
by elmimmo
2018-04-17T08:18:41-07:00
Forum: Users
Topic: Not like in the docs: Gradients in other Colorspaces
Replies: 2
Views: 1502

Not like in the docs: Gradients in other Colorspaces

When running any of the two example commands in Gradients in other Colorspaces to create a full rainbow gradient, convert -size 30x600 gradient:'#FFF-#0FF' -rotate 90 \ -set colorspace HSB -colorspace RGB \ gradient_rainbow_2.jpg the result is different depending on whether I output to JPEG or to TI...
by elmimmo
2016-12-08T11:45:03-07:00
Forum: Users
Topic: How to crop only when size is larger than X?
Replies: 5
Views: 3881

Re: How to crop only when size is larger than X?

You need to include the geometry specifiers, the "+0+0" part, with the crop dimensions. ... -crop 520x256+0+0 ... Ouch! Indeed, works! I am using this version: $ convert --version Version: ImageMagick 6.9.5-5 Q16 x86_64 2016-08-07 http://www.imagemagick.org Copyright: Copyright (C) 1999-2016 ImageM...
by elmimmo
2016-12-08T10:00:40-07:00
Forum: Users
Topic: Transparent bg + drop shadow + trim does not trim out transparent pixels
Replies: 9
Views: 5118

Re: Transparent bg + drop shadow + trim does not trim out transparent pixels

convert "input.png" \ \( "input.png" -alpha extract \) \ -matte -bordercolor none -border 100x100 \ -alpha off -compose copy_opacity -composite -compose over \ \( -clone 0 -background black -shadow 25x4+3+4 \) \ +swap \ -background none -layers merge \ \( -alpha extract -colors 256 -alpha off -comp...
by elmimmo
2016-12-08T09:44:22-07:00
Forum: Users
Topic: How to crop only when size is larger than X?
Replies: 5
Views: 3881

Re: How to crop only when size is larger than X?

convert in.png -gravity Center -crop 512x512+0+0 +repage out.png I tried with an image 520×256 , but -gravity seems not to be doing anything: cropping starts from the left with both -gravity center and -gravity east , with the a first output being 520×256. Then it outputs an additional file pertain...
by elmimmo
2016-12-08T08:46:21-07:00
Forum: Users
Topic: Transparent bg + drop shadow + trim does not trim out transparent pixels
Replies: 9
Views: 5118

Re: Transparent bg + drop shadow + trim does not trim out transparent pixels

the obvious way to do that is to extract the alpha, "-colors 256", and CopyOpacity it back to the image. Could you please rewrite my command above to include your suggested modification? I tried, but am not too sure would it should go (the alpha must be reduced to 8 bit after the generation of the ...
by elmimmo
2016-12-08T07:45:26-07:00
Forum: Users
Topic: Transparent bg + drop shadow + trim does not trim out transparent pixels
Replies: 9
Views: 5118

Re: Transparent bg + drop shadow + trim does not trim out transparent pixels

What version IM are you using? What Q-number, with or without HDRI? $ convert --version Version: ImageMagick 6.9.5-5 Q16 x86_64 2016-08-07 http://www.imagemagick.org Copyright: Copyright (C) 1999-2016 ImageMagick Studio LLC License: http://www.imagemagick.org/script/license.php Features: Cipher DPC...
by elmimmo
2016-12-08T02:35:31-07:00
Forum: Users
Topic: How to crop only when size is larger than X?
Replies: 5
Views: 3881

How to crop only when size is larger than X?

How can I crop an image to a maximum width × height (512×512), ideally also specifying -gravity center. If any of the image's dimension is lower than the specified size, it should be left as is. I.e:

600×600 → 512×512
200×600 → 200×512
600×200 → 512×200
by elmimmo
2016-12-08T01:05:17-07:00
Forum: Users
Topic: Transparent bg + drop shadow + trim does not trim out transparent pixels
Replies: 9
Views: 5118

Transparent bg + drop shadow + trim does not trim out transparent pixels

The color that -trim cuts out seems to be of a higher color depth than the output's, and therefore leaves in colors that in the output will be the same as the corner pixels onced rounded down to the output's color depth. How do I reduce the bit depth of ImageMagick's buffer so that -trim works based...