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crop to content

Alussam
I have scanned photographs which have a white border. I try "Crop to content"
and get the following popup:

"Cannot crop because the image is already cropped to its content."

The border is unchanged.

I thought that possibly there are some pixels on the outer edge of the border
that are confusing the crop, so I manully removed the outer edges of the border
and tried "crop to content" again. Same result.

What am I missing here?

Attachments:
* https://www.gimpusers.com/system/attachments/1353/original/two-women-300dpi-compr2-80.jpg

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Re: crop to content

Liam R E Quin
On Thu, 2020-01-30 at 20:44 +0100, geop wrote:
> I have scanned photographs which have a white border. I try "Crop to
> content"
Crop to content removes outside borders of picels which all have
exactly the same value but your border, although whiteish, is not like
that.

Rotate the image -- the easiest and fastest way is to use tool options,
turn on reverse/corrective mode, and turn on a grid "number of lines",
and change the number of lines until one lines up with the a vertical
edge in the border; drag the lines to rotate them a little and get the
grid line to match as well as possible, and then in case the image
isn't actually perfectly square, repeat for the top and bottom inner
border edges, then finally press Enter to do the rotation.

Then crop the iamge with the crop tool to get rid of the border, if
that's what you want, or to keep it, image->flatten image, then use
rectangle select to select the inner pictiure, select->invert to change
it to select the border, select->feather by 5px or so to make the edge
soft, and drag the white swatch from the toolbox into the selection (if
you don't have the default black and white, press d or click the
black/white icon that's near the swatch).

slave

PS: clean the prints with a microfibre cloth, and the top of the
scanner with that and eyeglass cleaner )spray onto the cloth of course,
notthe scanner, and not the same cloth you use for prints; you can also
use a special Japanese roller that was made for cleaning gramaphone
records, https://amzn.to/2U9jN3R - but i worry that it may lift the
surface of the print.

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with fabulous vintage art and fascinating texts to read.
Click here to have the slave beaten.

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crop to content

Alussam
Hi - thanks for the quick reply. I wondered if it had to do with the slight
non-uniformity of the pixel color in the border. I appreciate all your advice,
but I really wanted an "automatic" process because I have a LOT of these
bordered photos, and hoped to batch process them.

I see what you mean about rotation. My sample image is very slightly rotated,
and I would think my other images all have some version of the same issue. I can
tolerate that as these images are for family archives.

I should have mentioned that my main goal in eliminating the borders was so I
could use, in a batch process, Auto - White Balance to remove color casts from
many of the old B&W or color photos. From experimenting, the white border seemed
to mess this up. Without the border, the White Balance result seemed usually
"good enough" for my purpose.

So maybe I can suggest (somewhere) to the developers to add some parameters that
permit some range in values for the border color in "Crop to content".

Thanks again! I now understand what the issues are.


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Re: crop to content

Liam R E Quin
On Thu, 2020-01-30 at 23:09 +0100, geop wrote:
>
> So maybe I can suggest (somewhere) to the developers to add some
> parameters that
> permit some range in values for the border color in "Crop to
> content".
Once you do this you start eating into the main image, but it might be
an interesting option to have a "shrink wrap" option in rectangle
select or image crop, with a tolerance. Maybe there's already a script
or plugin that does this.

Auto white balance loses a little bit of detail. I'm not sure whether
rawtherapee or darktable has a way to do this - i tend to scan in 16bit
greyscale for things like this (although scanning in colour can make it
easier to remove dirt using the mono mixer and choosing blue and/or
green channels). Bt i'musually scanning to sell the pictures on
fromoldbooks.org.

The scanner i have came with holders for film strips and software for
Windows (silverfast i think) that knew about the holders and identified
all the photos automatically, a huge time saver.

If you can do a little scriptng you could maybe simply take a sample of
the middle of the image, use that for white balance, and then undo (in
the script) and apply the settings to the whole image.

It seems likely someone else has already done this, too...

slave

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Re: crop to content

Gary Aitken-2
In reply to this post by Liam R E Quin
On 1/30/20 1:44 PM, Liam Quin wrote:

> On Thu, 2020-01-30 at 20:44 +0100, geop wrote:
>> I have scanned photographs which have a white border. I try "Crop to
>> content"
> Crop to content removes outside borders of picels which all have
> exactly the same value but your border, although whiteish, is not like
> that.
>
> Rotate the image -- the easiest and fastest way is to use tool options,
> turn on reverse/corrective mode, and turn on a grid "number of lines",
> and change the number of lines until one lines up with the a vertical
> edge in the border; drag the lines to rotate them a little and get the
> grid line to match as well as possible, and then in case the image
> isn't actually perfectly square, repeat for the top and bottom inner
> border edges, then finally press Enter to do the rotation.
>
> Then crop the iamge with the crop tool to get rid of the border, if
> that's what you want, or to keep it, image->flatten image, then use
> rectangle select to select the inner pictiure, select->invert to change
> it to select the border, select->feather by 5px or so to make the edge
> soft, and drag the white swatch from the toolbox into the selection (if
> you don't have the default black and white, press d or click the
> black/white icon that's near the swatch).
>
> slave
>
> PS: clean the prints with a microfibre cloth, and the top of the
> scanner with that and eyeglass cleaner )spray onto the cloth of course,
> notthe scanner, and not the same cloth you use for prints; you can also
> use a special Japanese roller that was made for cleaning gramaphone
> records, https://amzn.to/2U9jN3R - but i worry that it may lift the
> surface of the print.
>

This is probably too simple a solution, but...
If the images are all the same size, and have roughly the same border,
can't you specify a rectangle select of a size slightly smaller to
eliminate the border, position it at the proper offset, and crop?
Or if the images are different sizes, compute a rectangle for e.g. 98%?

Gary
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crop to content

Alussam
In reply to this post by Alussam
>Hi - thanks for the quick reply. I wondered if it had to do with the
>slight
>non-uniformity of the pixel color in the border. I appreciate all your
>advice,
>but I really wanted an "automatic" process because I have a LOT of
>these
>bordered photos, and hoped to batch process them.
>
>I see what you mean about rotation. My sample image is very slightly
>rotated,
>and I would think my other images all have some version of the same
>issue. I can
>tolerate that as these images are for family archives.
>
>I should have mentioned that my main goal in eliminating the borders
>was so I
>could use, in a batch process, Auto - White Balance to remove color
>casts from
>many of the old B&W or color photos. From experimenting, the white
>border seemed
>to mess this up. Without the border, the White Balance result seemed
>usually
>"good enough" for my purpose.
>
>So maybe I can suggest (somewhere) to the developers to add some
>parameters that
>permit some range in values for the border color in "Crop to content".
>
>Thanks again! I now understand what the issues are.

Depends on your images but you might get away with the old divide-scanned-images
script. There are various enhanced versions but the original is worth a try.

Usually as its name, split up a page with several images but a single image
works.

Can be used individually or in a batch mode. Quick video demo, duration 2
minutes, using the batch function.

https://youtu.be/Ozc5WnlMnWY

Attachments:
* https://www.gimpusers.com/system/attachments/1354/original/DivideScannedImages.scm

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crop to content

Alussam
In reply to this post by Liam R E Quin
Just starting on this project, so I need to check on greyscale scanning of
greyscale images with color casts, versus color scanning with post-processing to
correct. So for now I'll put aside the greyscale images and just consider color
ones.

I'm scanning with a Fujitsu ScanSnap ix500. The automatic document feeding is
great. I does de-skewing, but I guess based on the sample image I posted, I now
realize it's not perfect in that respect.

I was not aware of rawtherapee or darktable. Will look around there some more.

I read more about how white balance is actually done - with multipliers - so I
now understand how that can blow out highlights in the red and blue channels.
Still might be OK for most images in a batch process, but of course I would
check each image and set aside those that need extra work.

I need to check the suggestion in the reply from rich404 - maybe one of the
scripts will do a "shrink wrap".

About your suggestion of doing auto white balance on a sample from the middle
image - where do I find in Gimp what new multipliers it chose?


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crop to content

Alussam
In reply to this post by Gary Aitken-2
Yes, there are certainly plenty of groups of images that are the same size, so
this could work.

>This is probably too simple a solution, but...
>If the images are all the same size, and have roughly the same border,
>can't you specify a rectangle select of a size slightly smaller to
>eliminate the border, position it at the proper offset, and crop?
>Or if the images are different sizes, compute a rectangle for e.g.
>98%?
>
>Gary

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crop to content

Alussam
In reply to this post by Alussam
Wow, Rich, just watched your video. Didn't realize until I start watching that
you had made a custom video using my image! Thanks!

On that image, the script worked extremely well, judging from the final image in
your video.

I see that the script file contained a link to a page describing how to install
it in Gimp. Unfortunately, I have other things I need to do now but I'll set it
up later on and give it a shot. Looks VERY promising.

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Re: crop to content

gimp-users.mbourne
In reply to this post by Liam R E Quin
Liam R E Quin wrote:

> On Thu, 2020-01-30 at 23:09 +0100, geop wrote:
>>
>> So maybe I can suggest (somewhere) to the developers to add some
>> parameters that
>> permit some range in values for the border color in "Crop to
>> content".
> Once you do this you start eating into the main image, but it might be
> an interesting option to have a "shrink wrap" option in rectangle
> select or image crop, with a tolerance. Maybe there's already a script
> or plugin that does this.

I'm no expert, but it seems that it should be possible to use the fuzzy
select tool (with adjustable threshold) to select the border, then
Select > Invert and Image > Fit Canvas to Selection?  Still with the
caveat that it may eat into the wanted image.

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Re: crop to content

Liam R E Quin
On Fri, 2020-01-31 at 21:47 +0000, [hidden email]
wrote:
>
> I'm no expert, but it seems that it should be possible to use the
> fuzzy
> select tool (with adjustable threshold) to select the border,

With a large enough threshhold to get most of the border this will
probably get part of the image inside; in addition, hairs and dirt on
the surface of the print make it hard.

It's possible to combine this with select->grow, but that's not really
easy to automate.

slave

>  then
> Select > Invert and Image > Fit Canvas to Selection?  Still with the
> caveat that it may eat into the wanted image.
>
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crop to content

Alussam
Late last night I got the latest version of the script suggested by Rich and
tried it on a dozen color photo scans with borders. Each was left with thin
"white" strips along the sides and top and bottom, mostly thicker at one end
than the other, indicating there was still a little skew left in the images
(though the script does a deskew). I'll need to vary the parameters, and also
try the original version of the script that Rich used.

I also tried the fuzzy select idea. With its default parameter (15, I think),
and using the greyscale photo I sent earlier, this selected a lot of sky area.
However, I did not get much further because I'm not familiar enough with Gimp. I
did open the fuzzy settings and lower the value, but nothing changed, so it was
unclear to me that was really the result, or that I had failed to completely
confirm the new parameter somehow. But now I'm in a situation where I can NOT
get to the fuzzy select settings any more, even on a Gimp restart! Arggh.

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crop to content

Alussam
Figured out my issues with fuzzy select and now know how to use it. Now after
lots of experimenting just with that sample greyscale photo, I conclude it does
NOT work well for my purpose. There is apparently too much variation in the
border area, so a low threshold does not get all of the border, and a higher
threshold eats into the image.

With the color picker, I found tone ranges in the border from 238 to 255. I
tried to pick midrange "starting pixels" for the fuzzy select, but one can't
really know if you clicked on exactly the right one.

The script still seems to have the most potential.

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crop to content

Alussam
In reply to this post by Alussam
>Late last night I got the latest version of the script suggested by
>Rich and
>tried it on a dozen color photo scans with borders. Each was left with
>thin
>"white" strips along the sides and top and bottom, mostly thicker at
>one end
>than the other, indicating there was still a little skew left in the
>images
>(though the script does a deskew). I'll need to vary the parameters,
>and also
>try the original version of the script that Rich used.
>

@geop

The divide scanned images script can use a separate compiled plugin deskew.exe
but no guarantee it will work correctly. Even older than the script. I have
tried it in Win10 and it does work (I usually use linux)

However going by the sample image, that is not the problem, the actual picture
area is not rectangular, if the side is vertical the top is not horizontal. Your
scanner has already made a good job of de-skewing. I think you already know
this.

If you can get it down to a minimum border, then any excess can be trimmed.
Manually it is:  Select All - Stroke Selection - Zealous Crop - Select None

I have knocked up a small python script (trim_it.py)  to apply that procedure.
It trims off about 8 pixels from the edges. Edit the script for more / less.
Find bottom of the tools menu.

If you need to batch,  then it is either run in command line, or use in the only
up-to-date GUI Gimp batch plugin BIMP see:
https://alessandrofrancesconi.it/projects/bimp/

Attached the two plugins zipped.

Unzip and put both  in C:\Users\"yourname"\AppData\Roaming\GIMP\2.10\plug-ins

Attachments:
* https://www.gimpusers.com/system/attachments/1355/original/trim.zip

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crop to content

Alussam
Running behind on trying things but here's an update.

I zoomed in on the photos processed by the version of the script I used (the
"new"version), and there is a 3-pixel-wide strip (of varying intensity and
color, if a color image) all around the edges that causes the visible artifacts
I see.

@rich404 I did not get to try it yet, but I expect that edge is what your trim
script would remove, with a setting of 3. I don't exactly understand yet how
your script works, but when I read about zealous crop, it seemed a bit risky.

Instead I tried "select all", brought up the rectangle select tool options, then
clicked inside the image to transfer the size and position info into the
options. From there, I could manually reduce the offsets by 3 and sizes by 6.
Then my lack of Gimp experience appears, because "Crop" does not remove the
pixels outside of the selection! I need to figure that out. However, this could
lead to a straightforward zealous-free way of cleaning up the script result.

Still need to try Rich's trim, and the original script.

@rich404 BTW, the new version script came with a deskew,exe but had me install
it elsewhere. It came from http://francoismalan.com. You can find it by
searching for "How to batch separate & crop multiple scanned photos".

@rich404 Regards bimp - I actually installed it the day before posting here,
figuring I would need it. Have yet to try it though.


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crop to content

Alussam
>Then my lack of Gimp experience appears, because "Crop" does not
>remove the pixels outside of the selection!

OK, figured that out. Had to use "Crop to selection" from Image menu instead of
Crop from Tools - Transform Tools.

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crop to content

Alussam
I found the simpler way to trim the 3 pixels from the edge. Select - All, then
Select - Shrink, specifying the 3 pixels.

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