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I was to superimpose two atom cloud images in Mathematica, with one cloud image centered on the other one. I have tried looking at other threads on this topic but haven't been able to get their solutions to work. I attached the two images to this post. The main issue is that I can't get rid of the white background when I try to overlay the image. Changing the opacity doesn't seem to help either. Ideally I would be able to overlay the images and adjust the transparancy of one relative to the other.

Note: In the final image, one of the clouds will need to be larger than the other by some factor that is ideally variable

atom cloud image atom cloud image 2

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You can turn the white material transparent:

ImageCompose[img2, ColorReplace[img1, White -> Transparent]]

enter image description here

To change the size, you can ImageResize. Here I have made the resize parameter variable with the slider:

Manipulate[ImageCompose[img2, 
  ImageResize[ColorReplace[img1, White -> Transparent], s]], {s, 50, 300, 1}]

enter image description here

There are also several options for the ImageCompose function and you might try them: you can put the object "on top of" or "xor with", etc.

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You can set the alpha channel relative to the pixel brightness - white pixels get transparent, darker pixels get more and more opaque:

addAlpha[img_] := 
 SetAlphaChannel[img, 
  ColorNegate[ImageAdjust[ColorConvert[img, "Grayscale"]]]]

Then you can use ImageCompose to combine them:

{a, b} = Import /@ {"https://i.stack.imgur.com/yPsWy.jpg", 
    "https://i.stack.imgur.com/dSvA2.jpg"};    
ImageCompose[b, addAlpha[a], {0, 0}, {0, 0}]

enter image description here

Or Inset to place the semitransparent images in another graphic:

ParametricPlot[{Sin[5 x], Cos[7 x]}, {x, 0, 2 \[Pi]},
 Epilog -> {
   Inset[addAlpha[a], {0, .5}, Center, 2],
   Inset[addAlpha[b], {.5, 0}, Center, 3]
   }]

enter image description here

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img1 = Import["https://i.stack.imgur.com/yPsWy.jpg"]
img2 = Import["https://i.stack.imgur.com/dSvA2.jpg"]

The images have different dimensions

ImageDimensions /@ {img1, img2}

{{61, 42}, {150, 103}}

and as noted some white frame, which can be removed with

{c1, c2} = ImageCrop /@ {img1, img2}

They still have different dimensions

ImageDimensions /@ {c1, c2}

{{47, 32}, {115, 78}}

so we'll resize the smaller one

im1 = ImageResize[c1, ImageDimensions@c2]
im2 = c2 (* for consistency of the naming *)

There are different way to compose the images, e.g.

ImageExposureCombine[{im1, im2}]

enter image description here

ImageMultiply[im1, im2]

enter image description here

Blend[{im1, im2}]

enter image description here

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  • $\begingroup$ So I actually need one of the clouds to look larger than the other, which is why I had the images be different sizes originally $\endgroup$ – user2476576 Nov 14 '16 at 19:02
  • $\begingroup$ There are another function ConformImages can uniform the image size. $\endgroup$ – yode Nov 14 '16 at 19:54

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