I've got 2 versions of 1 image
Is it possible to get a transparent png file representing this watermark? Can ImageMagick do this?
SilverMonkey has the basic solution using Imagemagick. But the request was for a transparent PNG. So I will add a little bit more to his code to make it transparent by adding -alpha copy.
convert kitty2.jpg kitty1.jpg -compose minus -composite -auto-level -alpha copy watermark1.png
Here is another approach that makes a binary mask for the watermark by thresholding. But it leaves a lot of noise. So I use some morphology open to remove the noise and then some morpholgy close to try to fill in where the text is broken up. Then I add -alpha copy to make the image transparent. But the text is white and the original watermark was light gray. So I turn alpha off, multiply by 0.75 to reduce the brightness of the white letters to gray without affecting the alpha channel. Then turn the alpha channel back on.
convert kitty2.jpg kitty1.jpg -compose minus -composite -threshold 0.6% -morphology open diamond:1 -morphology close octagon:1 -alpha copy -alpha off -evaluate multiply 0.75 -alpha on watermark2.png
For more on morphology, see https://imagemagick.org/Usage/morphology/
You can achieve your goal by calculating the difference between both images (subtract the pixels of both images and calculate the absolute value). This will result in:
ImageMagick seems to be capable of image subtraction, look here:
The code:
convert image2 image1 -compose minus -composite result
Related
I want to add logo on product image with engraving effect.
The original logo is
After adding it on the product it should look like this.
how to do this with imagemagick.
Using this as the trophy:
Then something along these lines:
convert trophy.jpg -gravity center \
\( G.png -colorspace gray -channel a -evaluate multiply 0.2 -resize 120x120 \) -composite result.png
So, I am basically loading the trophy, then in some "aside processing" in parentheses, loading the Google logo, converting it to greyscale, reducing the opacity by multiplying it by 0.2, resizing it and compositing it on top of the trophy.
By the way, if you were using GraphicsMagick, which doesn't have the parentheses I used to make sure I only convert the logo to greyscale and not the trophy, you would do it in a different order. First load the logo and process it (greyscale, resize etc), then load the trophy, then swap the order so the trophy goes to the background, like this:
gm convert G.png -colorspace gray -resize ... trophy.jpg -swap -composite result.png
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've got a PNG image with transparency:
original.png
Now I want to use ImageMagick to apply a diagonal gradient to its alpha channel. I mean so that its opacity remains in the top left corner, and gradually fades out to completely transparent in the bottom right corner. Like this:
result.png
So basically I want to generate a gradient, and use that as a mask for the image. But the image already has an alpha channel (transparency) of its own. Here's a visualisation of what I'm trying:
(original and result here displayed on checkerboard for visiblity, but I mean actual transparency)
I think I understand how to generate a diagonal gradient (the barycentric gradient command is very useful for this). But this creates a gradient in the color channels i.e. a colored or grayscale gradient. Whereas I want to apply the gradient on the alpha channel.
From the IM manual I understand the -compose CopyOpacity operator could be used for this. However this seems to copy the alpha from the mask on to my image. I need to "apply" this gradient color on my existing alpha channel, so basically I need my image's alpha channel to be multiplied by the grayscale color from the gradient image.
What would be the correct IM command line to perform the operation displayed above?
Here is one way you could do it:
convert tree.png -write MPR:orig -alpha extract \
\( +clone -colorspace gray -fx "1-j/h" \) \
-compose multiply -composite -write alpha.png \
MPR:orig +swap -compose copyopacity -composite result.png
The -write alpha.png can be omitted - it just shows the alpha layer for debugging and illustration purposes.
The MPR is just a temporary copy of the original image that I hold in memory while I am dinking around with the alpha channel and which I bring back near the end. The gradient in the alpha channel is generated by the -fx and I made the colorspace gray first so it only has to run once, instead of three times.
If you knew the dimensions of the tree image up front, you could replace the part in parentheses with:
-size WxH gradient:black-white
but I don't know the dimensions up front and I don't want a second convert command to get them, so I basically clone the original image's alpha channel to get a canvas the right size and fill it in with -fx.
I have two images. One is background with no alpha. The other is a white cloud. The alpha of the cloud image is premultiplied with black. When I composite them the white cloud has black in it, so it looks grey instead of white like it should. I'm doing:
convert -gravity Center bg.tga whitecloud.tga -composite comp.tga
Is there a way to composite premultiplied images in ImageMagick, or does the image have to be non-premultiplied? Can I make a premultiplied image non-premultiplied using ImageMagick?
Update:
Ok, here are the images as TGA for download:
http://acatysmoof.com/posting/problems/imagemagick/premultiplication/bg.tga
http://acatysmoof.com/posting/problems/imagemagick/premultiplication/whitecloud.tga
http://acatysmoof.com/posting/problems/imagemagick/premultiplication/aftereffects.tga
http://acatysmoof.com/posting/problems/imagemagick/premultiplication/imagemagick.tga
and in the same order as jpgs to view in your browser:
I tried all the modes provided, but none of them create the same result as After Effects.
It would be easier if you showed your images, but try adding -compose lighten before -composite in your command, like this:
convert a.tga b.tga -compose lighten -composite out.tga
Basically that will make ImageMagick choose the lighter pixel of the two images at every point.
If that doesn't work, try other blending modes
for b in $(identify -list compose); do
convert -label "$b" bg.tga whitecloud.tga -compose $b -composite miff:-
done | montage - -tile 5x out.png
I am kind of thinking Atop, Dissolve, SrcAtop and SrcOver might be your friends but have a look full-size and see what floats your boat. That would be
convert a.tga b.tga -compose Atop -composite out.tga
Here is an Imagemagick command that does what you want:
convert -gravity Center whitecloud.tga -fx "u/max(u.a, 1/255)" bg.tga +swap -composite -fx "u*u.a" comp.tga
What's happening here?
-fx command #1: Convert whitecloud.tga from premultiplied alpha to "normal". The max() operator is a special case to avoid dividing by zero.
+swap command: Make bg.tga the first image and the revised whitecloud.tga the second.
-composite these two regular, non-premultiplied images.
-fx command #2: take the result, and return to a premultiplied alpha format.
This gives exactly the same result as After Effects.
Note that, as I wrote it, it only works for an opaque bg.tga. You'd need to do some extra work to handle a transparent background image.
If you want to duplicate the After Effects result, then I believe what you want to do in ImageMagick is the following -- composite the background image with a white image using the cloud as a mask:
convert bg.tga \( -clone 0 -fill white -colorize 100 \) whitecloud.tga -compose over -composite cloud_blue.tga
I have posted a JPG result, but my .tga result is the same.
I'm trying to take an image, blur it with a 10px radius (both -blur and -gaussian-blur should work fine), then give it a 50% opacity, and finally overlay the blurred transparent image with the original. Here's what I've got so far:
convert sample.png \( sample.png -gaussian-blur 10 -matte -channel A
-evaluate set 50% \) -composite dreamy.png
Here's the original image:
And here is what it should look like after the effect is applied:
However, what I get with the command above just looks very similar to the original. Anyone have any ideas how to achieve the effect I want? If I do what I originally described in an image manipulation program, I get the desired effect, so something is probably wrong with the command I'm using.
Edit:
-adaptive-blur seems to get me closer to the desired effect, but still I'd like to use -blur.
Edit 2:
convert round-face-winslet.jpg \( +clone -blur 0x10 \) -compose Screen -composite round-face-winslet_soft.jpg
...gets me yet closer to the result, but no matter what kind of -compose method I choose, the result still does not look like the desired image. It's either too light or too dark. What should be a simple 50% opacity blended with the underlying original picture, for some reason doesn't want to work...
I think the effect you are looking for can be found in the ImageMagick compose examples in the "Softened Blurring" section.
convert face.png -morphology Convolve Gaussian:0x3 face_strong_blur.png
convert face.png face_strong_blur.png \
-compose Blend -define compose:args=60,40% -composite \
face_soft_blur.png
Looks like this:
An older tutorial on this technique (here) suggests lightening the blurred layer and blending in Multiply mode. I expect that darkening the blurred layer and blending with Screen would also work. Don't use a standard 50/50 blend - it doesn't have the same glowing appearance.
In your sample, the shadows of the processed image are lighter. Multiplying can only make an image darker, so I'm guessing they took the darken-Screen approach.