Legacy ImageMagick Discussions Archive

What version of Imagemagick. Different code is needed if on IM 6 vs IM 7.

Please read the topmost post in this forum at viewtopic.php?f=1&t=9620

Be aware that the mask image has pixels like RGB(50%,50%,0). Fred's command will create pixels from one image and alpha 50%, over pixels of another image with alpha 50%, over a "-background" colour. This may or may not be the desired effect. If it is, don't forget to set the required background colour.

snibgo wrote:Be aware that the mask image has pixels like RGB(50%,50%,0). Fred's command will create pixels from one image and alpha 50%, over pixels of another image with alpha 50%, over a "-background" colour. This may or may not be the desired effect. If it is, don't forget to set the required background colour.

Yes, snibgo is correct. I forgot about that. So perhaps it would be better to use -compose atop. Snibgo, do you have a better method? Also to be sure there is no unfilled color, then he is also correct about setting the background color or using one image as the background. Fill in what ever color you want for "somecolor"

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convert ( rgbmask.png -channel r -separate +channel image1.png +swap -alpha off -compose copy_opacity -composite ) ( rgbmask.png -channel g -separate +channel image2.png +swap -alpha off -compose copy_opacity -composite ) ( rgbmask.png -channel b -separate +channel image3.png +swap -alpha off -compose copy_opacity -composite ) -background somecolor -compose atop -composite result.png

Ah I see. This is good to know as a precaution.
I guess at this point I am more interested in using the size of image one as target size for images 2,3,4 and so on - I can use that as a common operation to make images the same size before doing operations that wouldnt work with them being different sizes.

For the resizing: in a Windows BAT command:

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for /F "usebackq" %%L in (`%IM%identify ^
  -format "WW=%%w\nHH=%%h" ^
  %SRC%`) do set %%L

Then:

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-resize "%WW%x%HH%^!"

for each other image.

For the mask problem: Any of the opaque inputs can be used as the "bottom-layer". Then apply each of the others, as Fred's command, with copy-opacity. However, that may not be the desired result.

If the mask has, for every pixel, R+G+B=100%, and the rule for compositing is "each output pixel should be R% of the first image, plus G% of the second, plus B% of the third" then we multiply each image by the appropriate channel and add the results. Something like (Windows BAT syntax, IM v6):

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convert
mask.png +write mpr:MASK +delete ^
( mpr:MASK -channel R -separate +channel image1.png -compose Multiply -composite ) ^
( mpr:MASK -channel G -separate +channel image2.png -compose Multiply -composite ) ^
( mpr:MASK -channel B -separate +channel image3.png -compose Multiply -composite ) ^
-compose Add -layers Merge ^
out.png

Snibgo's method is better than mine. Just to point a mistake with my method posted earlier. You can only do -compose ... -composite with two images at a time. So my method should more properly be as follows assuming that your mask will have no gaps between images:

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convert ^
( rgbmask.png -channel r -separate +channel image1.png +swap -alpha off -compose copy_opacity -composite ) ^
( rgbmask.png -channel g -separate +channel image2.png +swap -alpha off -compose copy_opacity -composite ) ^
-compose atop -composite ^
( rgbmask.png -channel b -separate +channel image3.png +swap -alpha off -compose copy_opacity -composite ) ^
-compose atop -composite ^
result.png

@snibgo - your solution is so far the best one! It seems to resize the three images to the size of the mask.

Is there a function in imagemagick's arsenal to resize a number of images to the size of a target image? Without the need to encompass it in a script.

Resize to a common size. You can specify the common size or get it from for example image 1

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convert image1 -format "%wx%h" info:
convert image1 image2 ... imageN -resize WxH resultimage

Result image will either be one image with multiple layers such as for TIFF or MIFF or multiple images with -0, -1 ... -N appended to the filename supplied for resultimage, such as for PNG or JPG.

But if the aspect ratios are not the same then you would need to either crop or pad the result using -extent WxH. Or force the images to be distorted to that exact size using the ! modifier. See http://www.imagemagick.org/script/comma ... p#geometry

In Imagemagick 7 this can be done in one command line.

@fmw42 How do you do it in one command line? The example code gives me errors and nothing happens to the images

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>convert out.png -format "%wx%h" info: convert b.png 2m.png ... imageN -resize WxH resultimage

convert: no decode delegate for this image format `INFO' @ error/constitute.c/Re
adImage/508.
convert: unable to open image 'convert': Permission denied @ error/blob.c/OpenBl
ob/2695.
convert: no decode delegate for this image format `' @ error/constitute.c/ReadIm
age/508.
convert: unable to open image '...': Permission denied @ error/blob.c/OpenBlob/2
695.
convert: no decode delegate for this image format `' @ error/constitute.c/ReadIm
age/508.
convert: unable to open image 'imageN': No such file or directory @ error/blob.c
/OpenBlob/2695.
convert: no decode delegate for this image format `' @ error/constitute.c/ReadIm
age/508.
convert: invalid argument for option '-resize': WxH @ error/convert.c/ConvertIma
geCommand/2578.

You have to be using IM 7 and then there is a different syntax that needs to be used.

In IM 7, you can do

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magick image1 -set option:mysize "%wx%h" image2 image3 ... imageN -resize "%[mysize]" result.png

You cannot do this in IM 6.

You still have not provided your IM version!

I am Using IM 7 ! Sorry

I still get errors and no result unfortunately :

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magick out.png -set option:mysize "%wx%h" b.png 2m.png ... imageN -resize "%[mysize]" result.png

magick: unable to open image '...': Permission denied @ error/blob.c/OpenBlob/2695.
magick: no decode delegate for this image format `' @ error/constitute.c/ReadImage/508.

Ok It worked after I removed the '...' and 'imageN'

@fmw42 How do you also tell the result images to have the name of their target counterparts? Yes, I want to overwrite the originals

blurymind wrote:@fmw42 How do you also tell the result images to have the name of their target counterparts? Yes, I want to overwrite the originals

Generally, magick or convert processes one input to one output. But mostly it can only have one output name.

So, get the size of the first image. Then write a loop over each input image and resize to the size of the first image and then save to the same input name.

Or get the size of the first image and then use mogrify to resize all the images in a folder. See http://www.imagemagick.org/Usage/basics/#mogrify

In Unix there are some special ways to handle this similarly. See http://www.imagemagick.org/Usage/basics/#mogrify_not

Legacy ImageMagick Discussions Archive

Composit 3 images using a single RGB mask

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Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask

Re: Composit 3 images using a single RGB mask