GIMP Version: 2.8.14
Operating System: Mac OS
OS Version: 10.10.2
GIMP Experience: New User

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I need help removing the background off bulk pictures (2400 of them). I prefer to change it to black but also transparent is OK...
the thing is the background color is blue but with different shades in it going from dark blue to light blue very close to white, the objects i have containing all the other colors (minus black and blue...)

can someone help me do this automatically or just explain how i can do it fast?

ty for all the help!!!

You could use the interactive foreground select 'GMIC filter under contour category' to cut it out.
If you have the patience you could also do it with the path tool then path to select, cut, paste as new image.

by the way, with your example do you want to leave the centre/pot plant stand, blue?

Are all of the subjects in the same location in all of the images? The reason I ask is that you'll need a garbage matte first to roughly isolate the subject, then a chroma key for the final mask. This is non-trivial, but possible if: a) the subject is consistently in the same location through all shots and b) no subject has colours close to your keying colour.

Also, you'll probably want something like imagemagick to actually do the bulk run.

Of course if you don't want a black background but transparent you dont need to add another layer.
EDIT: not sure what I did before (it did surprise me) I cannot do it again.
Anyway you will be better to follow Pat's advice.

in all the pics the objects are at the same spots but as you can see the plants may go out of the circle of the pot (even though the pot are located at the same spot)
and can you please explain a more- step by step for dummies please... I'm pretty goo at computers but a real newbie in photo editing\ GIMPing...

sallyanne- how time consuming was your try?

I am not at a computer at the moment (well, one with GIMP). But I will download and take a stab at it later. I'll probably just give you an imagemagick script (even if it only took 1 minute per image manually, you're looking at 40 hours of work across all your images).

Only 10 seconds

read the first post, only another 2399 remaining to process.

One possibility:
Open photos as layers (several?)
Use the GMIC (a single layer test)
Use Actions RWL http://gimpchat.com/viewtopic.php?f=9&t=11963

It's a start.
The rest should take about 40 minutes or so to do.

The GMIC "Extract objects" does leave slightly ragged edges, as this example shows:


You might do slightly better using decompose to select the background by hue.
(As you noted in your first post, the background luminosity varies considerably from near-white to near-black, but the hue does not vary.)

To select and replace the background by hue:
- open image
- Colors>Components>Decompose (color model = HSL, decompose to layers = YES)
in the decomposed image:
- Image>Mode = RGB
- File>Open as layer(s) ..load the same original image, turn-off visibility (toggle the eye icon)
- select "hue" layer
- Select by Color Tool ..select the background (which should be all the same gray-level in the "hue" layer)
- Select>Shrink (1px)
- Select>Grow (2px)
- select the original image layer and turn on visibility
- Bucket Fill Tool ..fill whole selection with black (or whatever)
- crop image to suit and export as jpg, etc

Result:


Note: both the above procedure and the GMIC Extract objects filter will leave some "funnies" and artefacts.
For example, there are white plastic plant-pot markers in the supplied image which reflect the background colour almost perfectly, so they get selected as "background" and replaced. Similarly with some parts of the rims of the pots which also reflect the background hue.

The above workflow could be scripted.
Question: do you actually want the images in pairs or separated?

I took a quick stab at it, and there will be some issues, but this may get you on a decent path... I am going to assume you've installed Imagemagick

First, I would do a garbage matte. That is, I would crop out all of the extraneous stuff in the image you don't care about. I would personally look at the image that has the biggest crop to get all of the plants in it, and use that. Open the image in GIMP, and do a rectangle select to get the dimensions:



Look carefully at the area outlined in red, as this will give you your crop + offset parameters.

In your directory of images, create a temporary output directory, CROP. Then run this imagemagick command to crop all of your images:



This will give you an entire sub-directory (CROP/) of pre-cropped images. Check those images to make sure that you don't need to adjust the crop parameters. If you do, you can just delete all the images in the sub-directory and re-run the command with new, adjusted parameters.

That step should at least be a little helpful no matter what final path you choose to key the images.

The next option worked semi-ok for me, but could probably have been better. I basically used this imagemagick command line to fuzz a color into transparency (if you don't need to retain filenames, you can use this command):



Obviously, replace the HEXCODEOFBGCOLOR with the correct hex code of your background (I think I used #63bdf9 from your image).



Adjust the fuzz parameter as needed to get a good result. It's a balancing act, but it's the fastest way to churn through 2400 images.

Another option I just thought about, if you're more comfortable approaching this as a chroma-keying exercise is to load up all of your images as as sequence in Blender, and use Blenders nodes to pull the key. There is already a keying and chroma-key node built into Blender to do this automatically, and you can simply have it output the results as png files as well.