I an trying to use Image Magick to create a new large png from several small png's but the smaller image do not have their transparency preserved. I am creating a 6000x6000 image and placing smaller png's at specific locations and some of them being rotated, this all works fine. The problem is that the small images don't have their transparency preserved when some of the small image overlap. This is an example of what I mean. I have tried several -channel options and -alpha on but nothing seems to work. What am i missing here?
Here is the commands I am using for my test.
convert -size 6000x6000 xc:none ^
( Rectangle_01.png -repage +200+200 ) ^
( Rectangle_01.png -repage +651+200 -rotate 45 ) ^
( Rectangle_01.png -repage +1102+200 -rotate -45 ) -flatten -alpha on test.png
Did you try:
-background none
none is one of the built-in color names for a fully transparent color.
I found this question when trying to solve a similar problem with the montage command, that would not preserve transparency. Setting a transparent background did fix my problem. The default background in ImageMagick is white.
There is a similar topic on http://www.imagemagick.org
"Try:
-fuzz XX% -transparent white
where the smaller the %, the closer to true white or conversely, the larger the %, the more variation from white is allowed to become transparent."
http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=12619
Related
I am trying to add a 10px red border to a transparent PNG using ImageMagick, while preserving any existing transparency that might exist within the image. Here is my source image:
If you download and view that image with an image viewer, you'll see that it has a transparent background.
According to everything I've read, the following Imagemagick command should add a 10px red border to the image:
convert input.png -bordercolor red -border 10 output.png
It actually does add the red border to the image, since the output dimensions are 20px larger in both directions. Unfortunately it also changes the background color of the image to red as well. Here is the output file:
I do not want the transparent area to be changed to red. I only want to add a red border around the transparent image.
I've tried using both ImageMagick version 6.9.10-23 (Ubuntu) and 7.1.0 (via CloudConvert API), with the same result. I've spent hours(!) trying to solve this.
What am I doing wrong?
I found the answer in this thread: https://legacy.imagemagick.org/discourse-server/viewtopic.php?t=31843 . Here are the two money quotes:
So, "-bordercolor red -border 2" should create an opaque red image 2
pixels larger than the input, and composite the input over this. As
your input is "-size 100x100 xc:none", the result should be 102x102
opaque red pixels. You might think this is "pretty obviously
incorrect", but it is the documented behaviour.
and
Nevertheless, you can get it to work to have the transparent inside,
if you add -compose copy before -bordercolor red -border 2 in both the
current IM 6 and IM 7. This just may have to be the way to do it from
here on, if there is a good reason for the changed behavior.
Here is the command that produces the result I am after:
convert -background transparent -bordercolor red -compose Copy -border 10 input.png output.png
Here's an answer that fully preserves the transparency
convert input.png +write mpr:INP -alpha extract -morphology dilate disk:10 \\( +clone -fill Black -colorize 100 \\) +swap -compose CopyOpacity -composite mpr:INP -compose Over -composite output.png
From https://legacy.imagemagick.org/Usage/crop/#extent
Here is a simple way to do that in Imagemagick. Change the compose setting from over to copy.
Input:
convert logo_transp.png -compose copy -bordercolor red -border 10 logo_transp_border.png
This is not a finding edge problem but I am trying to find the background color of the image, in order to find it, I am trying to get the edge of the image and guess the best color.
In order to do so, I want to remove the center of the image and just get image like a frame with transparent center.
Is it possible through ImageMagick?
For example
If want
Try this tested on Windows with IM V7:
magick "input.png" ( -size 200x200 xc:black ) -gravity center -compose DstOut -composite "output.png"
Takes the original photo, creates a rectangular mask, places it over the middle of the image and "cuts" out the rectangle
If the input is not a png ( for instance a jpg ) you will have to do some work setting the alpha channel
EDIT: This seems to work for both jpg and png images
magick "input.png" -alpha on ( -size 200x200 xc:black ) -gravity center -compose DstOut -composite "output.png"
I'll offer a simple variation on Bonzo's solution. This command allows you to specify in pixels the amount of edge you want to keep...
magick input.jpg -alpha on -bordercolor none -background none ^
( +clone -shave 24 -border 24 ) -compose dstout -composite output.png
It reads the input image, sets the alpha "on", and sets the border and background colors to "none".
Then inside the parentheses it makes a clone of the input image, shaves off the amount you want to retain around the edges, then adds that amount back as a transparent border all around. That will be the mask.
Then after the parentheses use a compose method of "dstout" to composite that mask onto the input image, which results in a transparent "hole" in the image with your specified amount of the original edge retained.
If you want to keep different amounts from the vertical and horizontal edges, specify those amounts in the shave and border operations...
... -shave 24x32 -border 24x32 ...
If you're using IMv7 you can even use FX expressions to specify the widths...
... -set option:v1 %[fx:(w+h)/2*0.1] -shave %[v1] -border %[v1] ...
The command is in Windows syntax using IMv7. Change "magick" to "convert" to use it with IMv6. To make it work in *nix you need to change the continued-line caret "^" to a backslash "\" and escape the parentheses with backslashes "\(...\)".
I am converting many 3D textures with imagemagick for a video game. My source files are png, my target files are png, too. But I notice that whenever the alpha channel drops to 0.0 my color information are gone (and I need them). I just want to scale all channels as they are. I guess there is a small switch that fixes that problem, but the deadline is near and I cannot find anything about that.
Simple command to reproduce this:
convert source-with-alpha.png -scale 2014 target.png (I also tried -resize and it also didn't work).
Doing just convert source-with-alpha.png target.png works fine though (but has no scaledown).
Thank you for your help.
I guess ImageMagick is trying to optimise something but not sure what/why. Maybe the idea is that if something is transparent you can't see it, so we might as well make it black so it compresses well.
Anyway, try separating the channels so they are all just treated as independent channels, then resizing and recombining:
convert input.png -channel RGBA -separate -resize XxY -combine result.png
I am not sure I understand your problem. I have no issue resizing a transparent PNG image with ImageMagick 6.9.10.28 Q16 Mac OSX with libpng 1.6.36. Perhaps you need to upgrade one or both.
Image:
Make white into transparent:
convert logo.png -transparent white logot.png
Resize it:
convert logot.png -resize 25% logot_small.png
I tried Mark Setchell answer with two different versions of Windows imagemagick but I still have this issue.
RGB becomes 0 if alpha is 0 when resizing.
A workaround was to add alpha a little bit so it becomes non-zero:
magic.exe input.tga -channel a -evaluate add 0.2% -channel RGBA -separate -filter Quadratic -resize -resize XxY! -combine result.tga
or also (same result)
magick.exe ( input.tga -alpha off -filter Quadratic -resize XxY! ) ( input.tga -filter Quadratic -resize XxY! -alpha extract -evaluate add 0.2% ) -compose Copy_Alpha -composite result.tga
("-filter Quadratic" is optional)
Post one of your tga files so we can test with it. What is your ImageMagick version? There should be no need for any switch. This works fine for me on IM 6.9.10.65 Q16 Mac OSX.
Make a transparent TGA:
convert logo: -transparent white logo.tga
transparent tga image
Resize by 50%
convert logo.tga -resize 50% logo2.tga
resized transparent tga image
I want to get the mean of a sequence of images by using Imagemagick. Therefore I use the following command:
convert *.png -evaluate-sequence mean MEAN.png
Each of my images does contain an alpha channel. What I want is: Combine all the images by ignoring the alpha channel.
When I combine the images, the alpha channel is considered in the "mean" method and my final image has transparency. That isn't what I want.
Result:
I tried to add the parameter -alpha off, but then Imagemagick converts the alpha channel to black.
convert *.png -alpha off -evaluate-sequence mean MEAN.png
Result:
Photoshop does it right. I load all images in a stack and create a smart object. When I use the "mean" method in Photoshop, the alpha channel is not considdered in the final result.
Result that I want with Imagemagick:
Does someone have an idea how to do that with Imagemagick?
What you need to do is to use the alpha channels as weighting images for each image. The total fraction of white values at each pixel from all the alpha channels would be the weight to use for the average. So something like this should do what you want or at least be close.
First, cd to your directory of images. Then run the following.
convert *.png -evaluate-sequence mean \
\( -clone 0 -alpha off \) \
\( -clone 0 -alpha extract \) \
-delete 0 +swap -compose divide -composite result.png
This will work if there is some image texture at each pixel coming from al least one image. That is at a given pixel all images are not totally black (transparent).
compare -metric rmse result.png mean_photoshop.png null:
125.167 (0.00190993)
So this shows that there is about 0.2% difference between my result and what you got from photoshop
Maybe this way of working will help you get there - or at least explain the problem:
convert xc:"rgba(255,0,0,1)" xc:"rgba(0,0,0,1)" xc:"rgba(0,0,0,0)" -depth 8 -evaluate-sequence mean txt:
Output
# ImageMagick pixel enumeration: 1,1,65535,srgba
0,0: (21845,0,0,43690) #550000AA srgba(85,0,0,0.666667)
Using IM 6.8.9.4 Q16 or IM 7.0.5.5 Q16 Mac OSX Sierra, this seems to work fine for me:
Make transparent image
convert logo: -transparent white logot.png
Get mean
convert logot.png logot.png logot.png -alpha off -evaluate-sequence mean result.png
magick logot.png logot.png logot.png -alpha off -evaluate-sequence mean result.png
This also seems to work:
convert logot.png logot.png logot.png -channel rgb -evaluate-sequence mean -alpha off result.png
So perhaps you need to upgrade your ImageMagick (and/or libpng?)
Can you post a zip file of some of your input images, so we can test with your images?
One problem that I see is that the PNG images that you provided have black under the transparent areas and not image texture. So when you disable alpha as in my commands above, you see black and the black gets averaged into the final result. Did you use these same PNG images in Photoshop or did you have Photoshop PSD images or some other images that you used and then exported to PNG, which may have put black under the transparent areas. Have you tried using the same PNG images in Photoshop to do the average?
In fact, you have 8-bit color (palette) images, which have one color (black) assigned to be the transparent color.
I have an image in .jpg format with white background color. I want to remove the white background color to transparent in Imagemagick. I tried many ways but still the white background can not be removed. Can some one help me to solve this.
You cannot have transparent background colors in your JPEGs. The JPEG file format doesn't support transparency.
If you need transparent background, you need to convert the JPEG to
either PNG (high quality, filesize possibly larger than JPEG)
or GIF (in case you can tolerate low quality and a range of maximally 255 colors).
Example command:
convert your.jpg -transparent white your.png
First, you need to convert the image format from .jpg to .png format, because JPEG does not support transparency. Then use this command:
convert image1.png -fuzz 20% -transparent white result.png
The -fuzz option allows the specified percentage deviation from the pure white colour to be converted to transparent as well. This is useful, for example, when your image contains noise or subtle gradients.
I just found a very neat thing!
magicwand 1,1 -t 20 -f image -r outside -m overlay -o 0 image.jpg imgOutput.png
It is a Fred Weinhaus bash script that can be downloaded from here (for non commercial use only). Also there has about 250 scripts!! and this one is amazing! it did exactly the trick, to remove all background while keeping the inner image dots untouched!
At his page, there are several images as examples so you pick what you need to put on the command line!
The initial position 1,1 is a general guesser saying all the contour is background.
Pay attention that the output must be ".png"
This is my solution without magicwand (replace magick by convert for im < 7.0):
magick img.png -fuzz 20% -fill none -draw "alpha 1x1 floodfill" result.png
Get the background automatically and remove it :
bg=$(convert input.png -format "%[pixel:p{0,0}]" info:)
convert input.png -fuzz 20% -transparent "$bg" output.png