CODEWITHSUNDEEP
imagemagick
spcsLrg
spcsLrg

Reputation: 377

ImageMagick: Cropping out sides and irregular borders to get a straight rectangular result

I have images like this. White border and a polygonal-ish swatches-like slanted-sides "inset" pictures in the middle with always four sides, although of varying side-angles, sizes and proportions

(Please note that these (examples) images are not the real images but I've made them to illustrate the exact sources I'll be working with.)

SOURCE IMAGES:

(The thick gray outlines are NOT part of the images below. I've added the gray outline just to make the original images stand out against stackoverflow pages' white background)

enter image description here enter image description here

PROCESSING DIAGRAM

I want to crop out the sides (including the outside white)...

enter image description here enter image description here

DESIRED RESULT

... so that I end up with a perfect largest possible straight-sided cropped rectangle from inside, and with no white around it, like so:

enter image description here enter image description here

I need to do this for images which will have different irregular insets, like these examples, in both portrait and landscape orientation.

(Other images will have different slants and the amount of white background border will vary, BUT will always have only four corners). So I'd need an adaptive, dynamic solution.

I was thinking, could it be possible by calculating white pixels of the four corners somehow, then cropping the sides one by one using the corner coordinates. The borders will be white, but the images are all jpegs so some "fuzz" percentage might be needed.

I've tried to do it by calculating white pixels from corners, but am struggling at how or what should be my steps in achieving that.

Can it be done?

(I'm on windows, with ImageMagick 7).

Upvotes: 0

Views: 231

Answers (1)

fmw42
fmw42

Reputation: 53089

You can do that in Imagemagick (6.9.12-54 or higher) using a special define for -trim.

(Some bugs have been found and fixed for -trim, so use the latest version of Imagemagick)

Image:

enter image description here

convert bubbles.jpg -background white -define trim:percent-background=0% -trim +repage result.jpg

Result

enter image description here

Upvotes: 2

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