Follow up on “Diff” an image using ImageMagick
When you are working with forms (as opposed to images), the changes are very hard to see with this technique. I wanted to show some type of yellow highlight maybe 10-20 pixels "bigger" (padding) around the actual pixels that changed.
So instead of just this
Something more like this
It seems like I am just missing something here in the stack that can make this work.
convert '(' file1.png -flatten -grayscale Rec709Luminance ')' \
'(' file2.png -flatten -grayscale Rec709Luminance ')' \
... here ? ...
'(' -clone 0-1 -compose darken -composite ')' \
... or here ? ...
-channel RGB -combine diff.png
I can also run this as separate commands and does not need to be fast, most of this is going to be run offline.
I also tried studying the technique here (specifically how the thumbnail scaling gives you the effect I want as the pixels get expanded) but this code is using the library instead of the ImageMagick command line tools. Line 248 => "make the red as visible as possible"
https://github.com/vslavik/diff-pdf/blob/master/diff-pdf.cpp#L218
An example form is the standard W-9. I made 2 subtle changes
PART II .. moved the 2. left about 2 pixels
PART II .. on 4., moved word is to the right 2 pixels
and the compare pumps out this (changes in red that you can barely see)
Thank you for any help
You can use -morphology dilate in Imagemagick to increase the size of the red areas. For example, using your two forms:
convert JW0wZ.png 1nHWT.png -compose difference -composite -morphology dilate disk:10 +level-colors black,red result.gif
UPDATE:
If you want the background transparent, then try
convert JW0wZ.png 1nHWT.png -compose difference -composite -morphology dilate disk:10 +level-colors "black,red" -fuzz 20% -transparent black result.png
Or better
convert JW0wZ.png 1nHWT.png -compose difference -composite -morphology dilate disk:10 -alpha copy -background red -alpha shape result2.png
Update 2: Here is how to overlay a 50% yellow marking onto you two originals. Change the value as desired. I create a difference image and dilate the white. Then I create a 50% yellow image. Then I composite each of the originals with the yellow using the difference image as a mask. See https://www.imagemagick.org/Usage/compose/#compose
convert JW0wZ.png 1nHWT.png \
\( -clone 0,1 -compose difference -composite -morphology dilate disk:10 \) \
\( -clone 0 -fill yellow -colorize 100 -channel a -evaluate set 50% +channel \) \
\( -clone 0,3,2 -compose over -composite +write 1.png \) \
\( -clone 1,3,2 -compose over -composite +write 2.png \) \
null:
To view this, if on Unix and have X11 installed, you can do
animate -delay 20 -resize 50% 1.png 2.png
Related
To demonstrate.
Original:
After ImageMagick:
I have some ideas:
Duplicate the image, crop the duplicate, then flatten the images together
Reverse mask?
Does anyone have any suggestions?
Although this has been successfully answered, I'll offer another simple approach using IMv6...
convert pasta.jpg -fill white \
\( +clone -evaluate set 25% -draw "roundrectangle 20,20 80,80 15,15" \) \
-compose multiply -composite result.png
After reading in the input image, in parentheses it clones the input and uses -evaluate to set the entire clone to 25% gray. A white "roundrectangle" is drawn on that gray image in the area you want to preserve. The mask looks like this...
Then after the parentheses, that mask and the input image are composited with -compose multiply. That leaves the white rectangle area as it was in the original input, and the rest of the image is multiplied by 0.25, leaving it darkened. The result...
This command should work just the same in IMv7 by changing "convert" to "magick". And it should work as well on Windows CLI by changing the continued-line backslashes "\" to carets "^", and removing any backslashes before the parentheses, so this "\(...\)" to this "(...)".
You can do that in Imagemagick by darkening the whole image, creating a round rectangle mask image, then composite the original with the darkened using the mask image.
Input:
convert pasta.jpg \
\( -clone 0 -brightness-contrast -75,0 \) \
\( -clone 0 -fill white -colorize 100 -fill black -draw "roundrectangle 20,20 80,80 15,15" -alpha off \) \
-compose over -composite \
pasta_rect.jpg
Result:
The ImageMagick documentation provides guidance on how to create torn page effects (https://www.imagemagick.org/Usage/thumbnails/#torn). However, in their implementation, all edges are torn. Suppose I wish to tear off only the bottom or top part of the image. How can I achieve such a thing using ImageMagick?
Simply grow the top & sides by using -extent operator.
convert zelda.png -background pink -extent 148x138-10-10 extent.png
(Adding pink background for visibility on stack)
Apply the effect from the Usage documentation.
convert extent.png \( +clone -alpha extract -virtual-pixel black \
-spread 10 -blur 0x3 -threshold 50% -spread 1 -blur 0x.7 \) \
-alpha off -compose Copy_Opacity -composite torn.png
Then crop back to original image size.
convert torn.png -crop 128x129+10+10 output.png
Update
If you do not want to use geometry, you can use a combination of -border, -shave & -chop.
convert zelda.png -bordercolor pink -border 10x10 -gravity South -chop 0x10 extent.png
convert extent.png \( +clone -alpha extract -virtual-pixel black \
-spread 10 -blur 0x3 -threshold 50% -spread 1 -blur 0x.7 \) \
-alpha off -compose Copy_Opacity -composite torn.png
convert torn.png -shave 10x -chop 0x10 output.png
.. And of course, this all can be done with one command.
convert zelda.png -bordercolor pink -border 10x10 -gravity South -chop 0x10 \
\( +clone -alpha extract -virtual-pixel black -spread 10 -blur 0x3 -threshold 50% \
-spread 1 -blur 0x.7 \) -gravity Forget -alpha off -compose Copy_Opacity -composite \
-shave 10x -chop 0x10 output.png
There are several ways to create a torn edge effect using ImageMagick. Here is another example command using IM version 6 and *nix syntax. This should apply a torn effect to just the top edge of any input image while keeping the original dimensions of the image.
convert input.png -alpha set -background black -fill white \
\( +clone -colorize 100 -gravity south -chop 0x6 -splice 0x6 \
-spread 6 -paint 2 +transparent white -blur 0x0.5 \) \
-background none -compose dstin -composite torn.png
That creates a white mask inside the parentheses. Then a small amount of the "torn" edge is chopped off and a black strip is spliced on to replace it. The random-ish torn edge is created using "-spread" and "-paint" between the white and black areas of the mask. After that, outside the parentheses, that mask is used to apply the transparent torn area to the input image.
To apply the effect to the bottom edge, just change the "-gravity north" to "-gravity south".
To make the torn edge on the left or right, change the gravity setting to "west" or "east", and change the values of the "-chop" and "-splice" operations from "0x6" to "6x0".
This should work the same way using ImageMagick version 7 by changing the "convert" command to "magick".
To use it in Windows, remove the backslashes that escape the parentheses from "\(...\)" to "(...)", and change the continued line backslashes "\" to carets "^".
I have a GIF image generated by a program where each output value is represented by its color via attached color palette. I need to replace one value, i.e. color from image with interpolated from neighboring pixels. Since I don't have possibility to alter programs output, I need to modify the output image. The resulting image will be saved in the PNG or GIF format.
I can easily extract (mask) all pixels that need repainting, since they have fixed color, but I was unable to find solution on how to replace a color of one/all pixels in imagemagick with interpolated color from neighboring pixels.
Is there a way to do this in imagemagick?
The raw values of the pixels are proportional to the physical value, so it would be great if the interpolation could be done on raw values that are then later transformed to the color via supplied color palette.
Attached image shows the original (left) and processed manually in GIMP (right).
One technique is to replace the offending color with the background, and then use a combination of erode & dilate morphology to remove the paths.
Given...
convert input.png \
-fill white -fuzz 10% -opaque black \
-morphology Erode Diamond \
-morphology Dilate Diamond \
output.png
It's not a true interpolate from nearest neighbors, but close. Also note the rounding errors across edges.
Updated
Or as Fred pointed out in the comments, just use -morphology Smooth Diamond instead of Erode + Dilate
convert input.png \
-fill white -fuzz 10% -opaque black \
-morphology Smooth Diamond \
output.png
Adding a bit to xenoid's suggestion, you want to create a mask image and use that to composite the median filter with the original, so that only the region about the line is changed. Using emcconville's image and ImageMagick:
convert img.png \
\( -clone 0 -statistic median 3x3 \) \
\( -clone 0 -fuzz 10% -fill white +opaque black -fill black +opaque white -negate \) \
-compose over -composite \
result.png
An alternate, but slightly longer approach, is to put the mask into the alpha channel of the filtered image and then composite it over the original, which produces exactly the same result:
convert img.png \
\( -clone 0 -statistic median 3x3 \) \
\( -clone 0 -fuzz 10% -fill white +opaque black -fill black +opaque white -negate \) \
\( -clone 1 -clone 2 -alpha off -compose copy_opacity -composite \) \
-delete 1,2 \
-compose over -composite \
result.png
Unfortunately, there is a slight dark residual to the upper left between the red and green. I tried increasing both the fuzz value and the filter size, but that did not seem to help. I am not sure why.
I'm trying to find a good way to add a 3px white stroke to a ton of png files, effectively to make them look like "stickers." I've got some sample code that does a decent job, but I can't seem to get the cropping right. Also, the stroke looks a bit pixelated and I wanted to know if it's possible to get cleaner edges!
I did a bunch of internet scouring, found some sample code, tweaked it around, and came to something that almost resembles what I'm looking for. The images are always going to be PNGs, so I looked into things like inkscape/gimp from the command line but realized I should be able to do this just using convert from the terminal.
convert in.png \
\( -clone 0 -alpha extract -threshold 0 \) \
\( -clone 1 -blur 10x65000 -threshold 0 \) \
\( -clone 2 -fill red -opaque white \) \
\( -clone 3 -clone 0 -clone 1 -alpha off -compose over -composite \) \
-delete 0,1,3 +swap -alpha off -compose copy_opacity -composite \
out.png
in:
out:
ideally:
Your main problem is it is that you do not have enough space bettween your object and the sides of the image. You just need to add your image with transparency and then remove any excess later.
In ImageMagick 6, this should do what you want.
1) read the input
2) add a larger border than you need to add
3) extract the alpha channel from the input and dilate it by the amount of border (in this case 10)
4) copy the previous image and color the white as red and the black as transparent
5) composite the original over the red/transparent image
6) delete the original and the red/transparent image
7) swap the composite with the dilated alpha channel and put the dilated alpha channel into the alpha channel of the previous image
8) trim the excess transparency from the border padding
9) save to output
convert img.png \
-bordercolor none -border 20 \
\( -clone 0 -alpha extract -morphology dilate diamond:10 \) \
\( -clone 1 -fuzz 30% -fill red -opaque white -fill none -opaque black \) \
\( -clone 2,0 -compose over -composite \) \
-delete 0,2 \
+swap -alpha off -compose copy_opacity -composite \
-trim +repage \
result.png
For ImageMagick 7, replace convert with magick.
If on a Unix-like system, you might be interested in my bash ImageMagick script, contour, at http://www.fmwconcepts.com/imagemagick/index.php
A better result can be achieved by replacing diamond:10 with disk:10
How can I remove two pixels wide lines (like the three lines in the image below) without altering the rest of the image, and repage it to its new minimum border ?
What you want to do is extract the alpha channel. Then use morphology close. Then put the result back into the alpha channel, then trim and save the result. In Imagemagick, that would be:
Input:
convert image.png \
\( -clone 0 -alpha extract -morphology open octagon:2 \) \
-alpha off -compose copy_opacity -composite \
-trim +repage \
result.png
Something like this maybe:
convert captcha.png -morphology erode disk:2 -trim +repage result.png