Text removal

[dognose]

I was looking at some of the new image manipulation features in Mathmatica.

Here is there example of Text Removal from an image:

http://www.wolfram.com/products/mathema ... Image.html

I'm wondering if anyone has any good ideas on how to reproduce these effects (or improve upon them) in IM

I was thinking of making a mask with the one color, then bluring the rest of the image and using that as the fill.

[fmw42]

I was looking at some of the new image manipulation features in Mathmatica.

Here is there example of Text Removal from an image:

http://www.wolfram.com/products/mathema ... Image.html

I'm wondering if anyone has any good ideas on how to reproduce these effects (or improve upon them) in IM

I was thinking of making a mask with the one color, then bluring the rest of the image and using that as the fill.

Here is how you do it, but you need my morphology script (http://www.fmwconcepts.com/imagemagick/index.html)

original duck:


two iterations of morphologic grayscale close:
morphology -m grayscale -t close -i 2 duck.png duck_close2.png


then subtract the latter from the former:
convert duck.png duck_close2.png -compose difference -composite duck_diff.png

(this is the bottom hat image)

then threshold the result
convert duck_diff.png -threshold 25% duck_diff_t25.png


Then do a binary morpologic dilate
morphology -m binary -t dilate duck_diff_t25.png duck_diff_t25_dilate.png

(you can cover over the top part of the image manually to get rid of the non-text white areas easy enough also, if you want by compositing a smaller black image from the top and which is just short of the text area. But I did not go that far here)

then composite the duck with the morphologic close using the last result as a mask
convert duck.png duck_close2.png duck_diff_t25_dilate.png -composite duck_comp_over.png


Voila, this keeps the original image where there was no text and the morphologic closed image where there was text (plus a little elsewhere, unfortunately)

[anthony]

To experiment I need a image to work with.

Code: Select all

convert rose: -gravity center -annotate 0 Anthony rose_label.jpg

Now I am not doing to try to figure out the mask from that as it is very dependant on the image that you would be dealing with, so I'll just generate it directly...

Code: Select all

convert rose: -gamma 0 -gravity center -fill white -stroke white -strokewidth 2 -annotate 0 Anthony  rose_mask.gif

Okay, lets do this... take image, use the mask to cut a hole in it, so as to remove the text, clone, blur and trash transparency to fill the hole with color, compose underneth the 'holely' image.

Code: Select all

convert rose_label.jpg \( rose_mask.gif -negate \) \
     -alpha off -compose CopyOpacity -composite \
    \( +clone -channel RGBA -blur 0x2 +channel -alpha off \) \
    +swap -compose Over -composite \
    text_removed_by_hole_blurring.jpg

However the blur is still leaving too much black in the resulting image, even though the

Not bad!!! It worked quite well, a LOT better than I expected!
Adding this to 'photos' section of IM examples, until a better place can be figured out (may take a few days to appear).
http://www.imagemagick.org/Usage/photos/#removing

ASIDE: rather than blurring, an alternative way would be edge diffusion, or the use of the new -sparse-colors operator to limit the colors involved to just the edges of the mask 'hole'.

Please play with these, and let me know how you go.

[anthony]

Using morphology to generate the replacement colors may be a better solution that a blur.

We really need to look at getting morphology operations, including a morphological skeleton, into IM at some point.

Here is the same image using a simplified mask, and the blur method, for comparision

Code: Select all

convert duck.png \( duck_mask.gif -negate \) \
          -alpha off -compose CopyOpacity -composite \
          \( +clone -channel RGBA -blur 0x1 +channel -alpha off \) \
          +swap -compose Over -composite  duck_removal_blur.png

As you can see blur does not work quite as nicely as morphology operators.
Though the mophological replacement image can be helps by adding a small sub-pixel blur.

There are however other methods that restore the color areas even better, I have seen articals on them, but can never seem to find them in my bookmarks when I want them. Fred may be able to help in this.

[fmw42]

Fred may be able to help in this.

The only other method I know is GREYCstoration inpainting. See my tests and links at http://www.fmwconcepts.com/misc_tests/G ... index.html

Look at the owl inpainting example (second from bottom on my page).

[dognose]

Wow, great results guys, really better than I expected!

With all those "date stamps" from modern film cameras, this should certainly help a lot.

The blur wouldn't work well if the text was more than a few pixels wide.

The GREYCstoration program seems pretty neat as well, I'll have to try that out.

[dognose]

Before


Mask:


After: using greycstoration inpainting


The results are quite interesting, and it certainly removes the text (a bit noticeably here, but the text isn't readable) The biggest problem I see is that the mask needs to be much more dialated than the text to remove it all. Better work with generating the mask I think would be helpful.

[anthony]

The reason for the mask needing to be so big is that the text has large color effects extending well beyond its nonomial boundary.

The cause for this is the use of low quality JPEG that has probably also been loaded and re-saved multiple times. The lossy nature of JPEG causes sharp color boundaries to spread out and diffuse over a larger region it is efforts to compress real-world images.

See IM Examples, Common File Formats JPEG, Lossy compression for more details.

The key here is to use a higher quality image if possible when removing text. though as text is on it, that may be asking a lot. I mean if you only have a copy of the image with text you probably do not have a good high quality source for the image.

[fmw42]

comment removed - See Anthony's reply