I want to convert to white any light shades of grey. I am using '-fuzz 10% -fill white -opaque #efeaee'. The problem is that the fuzz converts other colours other than grey, not just shades of grey (ie light yellow and light green get converted). I have tried to reduce the fuzz and repeat for various versions of grey but it really doesn't work and I'm sure there's a better way?
You can do that in ImageMagick, by converting to HSV colorspace. Then threshold the S and V channels. You want low saturation and high value combined as a mask. Then blend the input and a white image using the mask.
sthresh=10
vthresh=10
convert zelda1.jpg \
\( -clone 0 -fill white -colorize 100 \) \
\( -clone 0 -colorspace HSV -channel 1 -separate +channel -threshold $sthresh% -negate \) \
\( -clone 0 -colorspace HSV -channel 2 -separate +channel -negate -threshold $vthresh% -negate \) \
\( -clone 2,3 -compose multiply -composite -blur 0x1 \) \
-delete 2,3 \
-compose over -composite \
result.png
sthresh is the fuzz value for how close in color it is to white
vthresh is the fuzz value for how close it is in brightness to white
Values of zero mean exactly pure white.
Related
I have this face source image. I'm tyring to add a gradient to the bottom of the picture so it fades out alpha transparent.
Problem is that the transparent source image is not transparent anymore after sparse-color transformation - the transparent area is now black.
This is my cmd so far:
magick convert face.png -alpha set -background none -channel A -sparse-color barycentric "0,%[fx:h*0.90] white 0,%[h] none" +channel face-gradient.png
Here is how you have to do that in Imagemagick. Your image already has an alpha channel. So you have to create a new grayscale gradient image as a mask and combine that with the existing alpha channel. (The -sparse-color is going to write over your existing alpha channel.)
magick face.png \
\( -clone 0 -alpha extract \) \
\( -clone 0 -sparse-color barycentric "0,%[fx:h*0.90] white 0,%[h] black" \) \
\( -clone 1,2 -compose multiply -composite \) \
-delete 1,2 \
-alpha off -compose copy_opacity -composite face-gradient.png
I would like to colorize an image with two colours, red on the left half and green on the right half but the colorize function just adds a coloured overlay to the image rather than multiplying it on. So I would like my image to look like this but it is currently looking like this. Here is the original image
My code at the moment is this:
convert normal.png \
\( -clone 0 -crop 50x100% -fill red -colorize 60% \) \
\( -clone 0 -crop 50x100%+64 -fill green -colorize 60% \) \
-delete 0 -background none -flatten result.png
I have tried adding -compose multiply -composite to the code but I just get this which has the right effect but I cannot get it to the position that I want, heres the code for that:
convert normal.png \
\( -clone 0 -crop 50x100% -fill red -colorize 70% \) \
\( -clone 0 -crop 50x100%+64 -fill green -colorize 70% \) \
-background none -compose multiply -composite result.png
One simple approach would be to assemble the red-green overlay inside parentheses, then do a multiply composite over the input image.
magick lena_circ.png -size %wx%h \
\( xc:red xc:green +append -scale 50x100% \) \
-compose multiply -channel rgb -composite result.png
That command give me this result...
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 do I replace a color in an image which contains transparency with ImageMagick, but afterwards retain the transparency of the original image.
This is very useful for batch-changing of colors in icons.
Updated Answer
Option 1
A simpler option might be like this:
convert start.png -alpha deactivate -fill blue -opaque red -alpha activate result.png
which changes this:
to this:
Option 2
Another option, which uses an in-memory copy of the image, can also avoid the need to create 2 processes and write an intermediate file to disk:
convert start.png -write MPR:orig \
-alpha off -fill blue -opaque red \
MPR:orig -compose CopyOpacity -composite result.png
Option 3
Yet another method, that uses clone instead of MPR:
convert start.png \
\( +clone -alpha off -fill blue -opaque red \) \
+swap -compose CopyOpacity -composite result.png
Original Answer
If I create an image that contains transparency like this:
convert -size 400x400 xc:none -fill red -draw "rectangle 10,10 100,100" -fill blue -draw "rectangle 200,200 300,300" -bordercolor black -border 5 start.png
I'll get this (I am showing it overlaid on a checkerboard just to visualise the transparency):
If I now run this
convert start.png -fill yellow -opaque red result.png
I'll get this (again overlaid on a checkerboard):
Not sure why you need a more complicated, 2-stage process - or have I misunderstood your question?
convert file-in.png -alpha off -fill REPLACEMENT -opaque COLOR file-out.png
then
convert file-out.png file-in.png -compose CopyOpacity -composite PNG32:file-final.png