Erasing the background

An example of erasing the background "in the wild"
MIM Curator Saskia ... shows how photos were made when in Gambia ? taking pictures of local instruments.

http://diversions.lan/home/pi/2016-10-13/P1018918.webm#t=00:03:18

http://mim.be/hajhouj?from_i_m=1
Example of photograph from the musical instruments museum: background is neutral; the description of the context is moved into the text

• Thursday. After the intoxicating smells and colours of the tannery souk, we continue our stroll along the Mohassine alleyway in a northerly direction. Soon we come to a shop selling musical instruments. We go inside. Like all Moroccan instrument shops, it is crammed from top to bottom with instruments of every description. My eye is drawn to a beautiful guembri or hajhouj, the 'bass guitar' of the Gnawa people. This one, it seems to me, would be perfect for the mim. The shopkeeper built it himself, and - even more interesting - it turns out he is a maâlem (gnawa master). His full name is Mohammed Ben Boujamaâ Filali, Ben Boujamaâ for short, the son of Boujamaâ. I tell him I want to buy the hajhouj, but that I would also like to make a recording of it. Ben Boujamaâ has a suggestion: I pay a deposit now and come back the next morning at 10 o'clock for a short gnawa session in his workshop. He will make sure the cantor of his group is there.      
• ...

http://mim.be/sites/default/files/instruments/2009.024_04.jpg

tarzan? https://archive.org/details/TarzanoftheApes1918AndyDivx


http://docs.opencv.org/trunk/d1/dc5/tutorial_background_subtraction.html
Background subtraction: technique usually used in video
every time you have a new frame, the code makes a diff and substracts the element that stands out
simple algorithm that presupposes you have the opportunity to come to a clean slate of the background
if you don't have this reference you have to make the algorithm learn what counts as a difference: have a large amount of footage that teaches the algorithm what makes a difference

in the museum context, we don't have enough images for the algorithm to learn
other techniques: the selection of the color of the background we want to remove

Gimp: Foreground Select Tool
two stages: first you use the lasso tool to select a large area that contains the object, second stage is a pen with which you can select vaguely the outlines of the object. then becomes a selection

Gimp->Filters->Python Fu->Console

http://sicv.activearchives.org/video/vitrine.hardsubs.webm

peter .... use the profiles as a mask...

Cristina: interest in what's left over in the backround (other objects, furniture)

writing a script for gimp:

• img=gimp.image_list()[0]
• drw=pdb.gimp_image_active_drawable(img)
• width=pdb.gimp_image_width(img)
• height=pdb.gimp_image_height(img)
• ctrlPoints=[0,0,width,height]
• pdb.gimp_paintbrush_default(drw,len(ctrlPoints),ctrlPoints)
• 
  

it's a sort of emulation of the behaviour of the user, but only according to a series of procedures that are available to the user

existing plugin: Remove Photo Image Background Color


Gimp-Python

https://www.gimp.org/docs/python/index.html

http://web.archive.org/web/20111104203020/http://www.exp-media.com/content/extending-gimp-python-python-fu-plugins-part-4