Change color of some regions

[cgkas]

Hello to all,

I have an image like this (I get this image applying convert input.png -alpha extract -negate out.png):



I would like
1- to change the internal black squares to red
2- change the white rectangles to red. These white rectangles have some pixels in black inside.

The output I´m looking for is like this:



Is there a way to make this?

Thanks in advance for any help.

[snibgo]

Please, always tell us the version of IM you use, on what platform.

I suggest you use a floodfill. See http://www.imagemagick.org/script/comma ... #floodfill

[cgkas]

Hello snibgo,

Thanks for answer.

IM version is 6.9.10-11 Q16 x86_64.

I didn't say in my original post but I'd like to change to red those regions automatically, if possible, without say the x,y position, because my final goal is to be able to get the coordinates of the red regions.

Thanks again.

[snibgo]

What other constraints are there on these images?

For this image, "-connected-components" can be used to find the bounding boxes and centroids.

Code: Select all

magick small.png -threshold 50% -define connected-components:verbose=true -define connected-components:area-threshold=10 -connected-components 4 NULL:

Objects (id: bounding-box centroid area mean-color):
  0: 30x30+0+0 14.6,15.1 509 srgb(0,0,0)
  12: 10x9+3+14 7.5,18.0 90 srgb(0,0,0)
  13: 10x9+17+14 21.5,18.0 90 srgb(0,0,0)
  1: 12x5+2+2 7.5,4.0 57 srgb(255,255,255)
  2: 11x5+16+2 21.0,4.0 49 srgb(255,255,255)
  10: 12x14+2+10 7.5,17.1 48 srgb(255,255,255)
  11: 12x14+16+10 21.5,17.1 48 srgb(255,255,255)
  4: 1x2+19+3 19.0,3.5 2 srgb(0,0,0)
  6: 2x1+8+4 8.5,4.0 2 srgb(0,0,0)
  9: 1x1+23+5 23.0,5.0 1 srgb(0,0,0)
  8: 1x1+20+5 20.0,5.0 1 srgb(0,0,0)
  5: 1x1+22+3 22.0,3.0 1 srgb(0,0,0)
  3: 1x1+7+3 7.0,3.0 1 srgb(0,0,0)
  7: 1x1+21+4 21.0,4.0 1 srgb(0,0,0)

srgb(0,0,0) is black and srgb(255,255,255) is white.

The two black entries size 90 pixels, and the two largest white entries, are the ones you want.

[cgkas]

Excellent snibgo. Thanks so much.

Actually I tested in real image that have several colors (not only black and white) and it seems to print the info for the squares I want to isolate.

It seems your code sees only white and black, having this I don't need 2 extra commands I sent previously to convert the image in black and white only.

The only thing I see is the command "magick" doesn't work for me (command not found). I tried with convert intead of magick and it works but the print is shorter.

Code: Select all

$ convert small.png -threshold 50% -define connected-components:verbose=true -define connected-components:area-threshold=10 -connected-components 4 NULL:
Objects (id: bounding-box centroid area mean-color):
  0: 30x30+0+0 14.6,15.1 509 srgb(0,0,0)
  13: 10x9+17+14 21.5,18.0 90 srgb(0,0,0)
  12: 10x9+3+14 7.5,18.0 90 srgb(0,0,0)
  1: 12x5+2+2 7.5,4.0 60 srgb(255,255,255)
  2: 11x5+16+2 21.0,4.0 55 srgb(255,255,255)
  10: 12x14+2+10 7.5,17.1 48 srgb(255,255,255)
  11: 12x14+16+10 21.5,17.1 48 srgb(255,255,255)

One question, since this is a part of a bigger script. Do you know if this command will work with RMagick and its equivalent?
Or would be more compatible some solution with python than Ruby?

Thanks

[snibgo]

Sorry, I forgot you are using v6. Yes, the v6 program is "convert".

I know nothing about Ruby or RMagick, and only a little Python. All my IM work is either command-line or C.