Crop to selection

[JosseF]

"Crop to selection" would be really useful (for me). It would allow to automate (batch) cropping based on a background color.

[carl123]

Crop to selection can be done in a macro but I don't understand this...

5 hours ago, JosseF said:

It would allow to automate (batch) cropping based on a background color.

Can you be more specific about what you want to do?

[JosseF]

This is for automated cropping of reproduction photography.
E.g. a drawing is shot against a black background.
In Photoshop I set a selection of black, invert the selection, enlarge it by 20 pixels (to leave a margin around the drawing) and then do a crop to selection.
As far as I can tell I can't do that or something similar in Affinity Photo.

[John Rostron]

You can copy your selection and then select File > New from Clipboard.

John

[carl123]

1. Use the Flood Select Tool to select the background
2. Press the Delete key to delete it
3. Use Select > Invert Pixel Selection to invert the selection
4. Use Select > Grow / Shrink  to enlarge the selection by 20px
5. Use Document > Clip Canvas to "crop to selection"

Steps 2-5 can be made into a macro, Step 1 may also be possible in a macro it just depends on how "complex" or contiguous the background is.

If Step 1 is also recordable in a macro you can then use File > New batch Job to automate the process across several images

If the above is unclear or does not work for you we would need some samples of the images you work with in order to give more insightful information

  

[JosseF]

Thank you for your assistance. It is getting close to what I want to do, but not quite.

In step 2 the background is deleted. That is not allowed in cultural heritage photography as it may remove a few pixels from the object being reproduced.

That is why I have to leave a 20 pixel margin around the object.

I tried leaving out that step, but then the Document > Clip Canvas doesn't work anymore.

I also tried a variation where I first inverted the selection, enlarged it by 20 pixels, inverted it again, deleted the background and finally inverted it once more.

Now Document > Clip Canvas works, but (unless the object is perfectly rectangular and perfectly parallel to the image) I am left with an irregular edge on the outside of the selection.

[Old Bruce]

Try this macro for the first three steps Add 20 pix.afmacro  

Select the background

Invert the selection

Grow the selection

   Now you have to

   Copy (Command + C)

   Make a new document from the clipboard. File > New From Clipboard (Command + Option + Shift + N)

You should have 20 pixels of black background around the picture.

[JosseF]

Thanks for the suggestion, but still not the solution.

I made a couple of example images, no. 1 is an irregular shaped object against a dark background:

 

No. 2 is how I would like to have it cropped:

 

No. 3 is the result of using carl123's suggestion:

 

No 4. is the result of using Old Bruce's suggestion: