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Is there a SubImageApply?

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5

1

$begingroup$

Given an image and a subimage (as a rectangle or pixel ranges):

img = ExampleData[{"TestImage", "Lena"}];

f = FindFaces[img]; HighlightImage[img, f]

How would one apply operations just that sub-image, leaving the rest of the pixels unchanged?

(* would maybe be something like this *)

ImageConvolve[img, BoxMatrix[1]/11, "MapAt" -> f]

ImageApply[Max, img, "Subimage" -> f]

Is there a built-in or slick way to this (without resorting to ImageData and MapAt)? I thought there was something like this added in 12, but was perhaps mistaken. If not, ImageMapAt or ImageApplyAt or some such thing would surely make a nice repository function.

image-processing image

share|improve this question

edited 2 days ago

M.R.

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  For that matter, doesn't look like FindFaces returns index slices, only less useful rectangles.
  $endgroup$
  – M.R.
  2 days ago
  

  
  
  
  

add a comment | 

5

1

$begingroup$

Given an image and a subimage (as a rectangle or pixel ranges):

img = ExampleData[{"TestImage", "Lena"}];

f = FindFaces[img]; HighlightImage[img, f]

How would one apply operations just that sub-image, leaving the rest of the pixels unchanged?

(* would maybe be something like this *)

ImageConvolve[img, BoxMatrix[1]/11, "MapAt" -> f]

ImageApply[Max, img, "Subimage" -> f]

Is there a built-in or slick way to this (without resorting to ImageData and MapAt)? I thought there was something like this added in 12, but was perhaps mistaken. If not, ImageMapAt or ImageApplyAt or some such thing would surely make a nice repository function.

image-processing image

share|improve this question

edited 2 days ago

M.R.

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  For that matter, doesn't look like FindFaces returns index slices, only less useful rectangles.
  $endgroup$
  – M.R.
  2 days ago
  

  
  
  
  

add a comment | 

$begingroup$

Given an image and a subimage (as a rectangle or pixel ranges):

img = ExampleData[{"TestImage", "Lena"}];

f = FindFaces[img]; HighlightImage[img, f]

How would one apply operations just that sub-image, leaving the rest of the pixels unchanged?

(* would maybe be something like this *)

ImageConvolve[img, BoxMatrix[1]/11, "MapAt" -> f]

ImageApply[Max, img, "Subimage" -> f]

Is there a built-in or slick way to this (without resorting to ImageData and MapAt)? I thought there was something like this added in 12, but was perhaps mistaken. If not, ImageMapAt or ImageApplyAt or some such thing would surely make a nice repository function.

image-processing image

share|improve this question

edited 2 days ago

M.R.

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

$endgroup$

img = ExampleData[{"TestImage", "Lena"}];

f = FindFaces[img]; HighlightImage[img, f]

(* would maybe be something like this *)

ImageConvolve[img, BoxMatrix[1]/11, "MapAt" -> f]

ImageApply[Max, img, "Subimage" -> f]

share|improve this question

edited 2 days ago

M.R.

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

share|improve this question

edited 2 days ago

M.R.

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

asked 2 days ago

M.R.M.R.

15.4k66 gold badges6161 silver badges204204 bronze badges

1 Answer
1

active

oldest

votes

6

$begingroup$

Assuming f matches {__Rectangle}:

subImageApply[image_Image, sub : {__Rectangle}, filter_] := Fold[

  ImageCompose[#, #2[[1]], #2[[2]], {0, 0}] &

, image

, { filter @ ImageTrim[image, #],  #[[1]] } & /@ sub

]



subImageApply[img, f, Blur[#, 12] &]

You can use ImageConvolve or whatever you need instead of Blur.

Fold is there to account for multiple rectangles.

share|improve this answer

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Elegant! Thanks :) I think if they just added "Masking" option to every image operation that would be super
  $endgroup$
  – M.R.
  2 days ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @M.R. You are welcome. I expected it to be easier but that is fine enough I guess. Otoh image-processing is not my area so maybe I missed something.
  $endgroup$
  – Kuba♦
  2 days ago
  

  
  
  
  

add a comment | 

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6

$begingroup$

Assuming f matches {__Rectangle}:

subImageApply[image_Image, sub : {__Rectangle}, filter_] := Fold[

  ImageCompose[#, #2[[1]], #2[[2]], {0, 0}] &

, image

, { filter @ ImageTrim[image, #],  #[[1]] } & /@ sub

]



subImageApply[img, f, Blur[#, 12] &]

You can use ImageConvolve or whatever you need instead of Blur.

Fold is there to account for multiple rectangles.

share|improve this answer

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Elegant! Thanks :) I think if they just added "Masking" option to every image operation that would be super
  $endgroup$
  – M.R.
  2 days ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @M.R. You are welcome. I expected it to be easier but that is fine enough I guess. Otoh image-processing is not my area so maybe I missed something.
  $endgroup$
  – Kuba♦
  2 days ago
  

  
  
  
  

add a comment | 

6

$begingroup$

Assuming f matches {__Rectangle}:

subImageApply[image_Image, sub : {__Rectangle}, filter_] := Fold[

  ImageCompose[#, #2[[1]], #2[[2]], {0, 0}] &

, image

, { filter @ ImageTrim[image, #],  #[[1]] } & /@ sub

]



subImageApply[img, f, Blur[#, 12] &]

You can use ImageConvolve or whatever you need instead of Blur.

Fold is there to account for multiple rectangles.

share|improve this answer

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Elegant! Thanks :) I think if they just added "Masking" option to every image operation that would be super
  $endgroup$
  – M.R.
  2 days ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  @M.R. You are welcome. I expected it to be easier but that is fine enough I guess. Otoh image-processing is not my area so maybe I missed something.
  $endgroup$
  – Kuba♦
  2 days ago
  

  
  
  
  

add a comment | 

$begingroup$

Assuming f matches {__Rectangle}:

subImageApply[image_Image, sub : {__Rectangle}, filter_] := Fold[

  ImageCompose[#, #2[[1]], #2[[2]], {0, 0}] &

, image

, { filter @ ImageTrim[image, #],  #[[1]] } & /@ sub

]



subImageApply[img, f, Blur[#, 12] &]

You can use ImageConvolve or whatever you need instead of Blur.

Fold is there to account for multiple rectangles.

share|improve this answer

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges

$endgroup$

subImageApply[image_Image, sub : {__Rectangle}, filter_] := Fold[

  ImageCompose[#, #2[[1]], #2[[2]], {0, 0}] &

, image

, { filter @ ImageTrim[image, #],  #[[1]] } & /@ sub

]



subImageApply[img, f, Blur[#, 12] &]

share|improve this answer

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges

answered 2 days ago

Kuba♦Kuba

111k1212 gold badges220220 silver badges567567 bronze badges