Search found 28 matches

by elmimmo
2020-02-04T04:45:32-07:00
Forum: Users
Topic: From PNG to TIFF with premultiplied alpha?
Replies: 3
Views: 920

Re: From PNG to TIFF with premultiplied alpha?

This is the input (enter in URL address and save as in.png) data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAKAAAACQAgMAAADy24gTAAAADFBMVEX///8AAAAAAAAAAAD4jAJNAAAABHRSTlMAc3mA9mHxDAAAAEdJREFUWMPt1qERgDAQRcFTGERap45URQl0QBr44iaCQezTW8CrkiR93TFDV4DjDT0BngneIAiCIAiCIAhuwPaHt89ekvSTFu26DY5mdiViAAAAAElFTk...
by elmimmo
2020-02-03T08:38:13-07:00
Forum: Users
Topic: From PNG to TIFF with premultiplied alpha?
Replies: 3
Views: 920

From PNG to TIFF with premultiplied alpha?

How do I output to TIFF with alpha premultiplied?

Code: Select all

convert in.png -define tiff:alpha=associated out.tif
That seems to tag the alpha as premultiplied but not do the premultiplication itself. Input and output look different.

Input is RGB+A with 8-bit channel depth. ImageMagick is version 7.0.9-20.
by elmimmo
2019-02-01T02:56:26-07:00
Forum: Bugs
Topic: Inefficient compression of CMYK images
Replies: 5
Views: 9096

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: 9096

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: 9096

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: 2480

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: 2460

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: 2460

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: 2480

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: 5060

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: 6829

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: 5060

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: 6829

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: 6829

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...