How to global balance contrast of mosaiced image. about pyvips HOT 6 OPEN

Yes, global balance will work on merged images too.

You might need to run it in sections, so balance 10x10 blocks of tiles, then balance again after final assembly.

from pyvips.

Can you give please an example to integrate this with merge function?
My code looks like.

1. def stitch(coor):
2.     global onlyfiles,mypath,row,column
3.     onlyfiles=np.array(onlyfiles)
4.     files=onlyfiles.reshape(row,column)
5.     blend=False
6.     for r in tqdm(range(files.shape[0])):    
7.         c=0
8.         if r==0:
9.             tile = pyvips.Image.black(coor[r,c][0],coor[r,c][1])
10.         else:
11.             tile = pyvips.Image.black(coor[r,c][0],coor[r,c][1]-coor[r-1,c][1])        
12.         for c in tqdm(range(files.shape[1])): 
13.             tile1 = pyvips.Image.new_from_file(join(mypath,files[r][c]), access="sequential")
14.             if r==0:
15.                 x,y=coor[r,c]
16.             else:
17.                 x,y=coor[r,c][0],coor[r,c][1]-coor[r-1,0][1]
18.             tile = tile.merge(tile1, 'horizontal', -x, -y, mblend =blend)
19.         if r>0:
20.             y=coor[r-1,0][1]
21.             stitch_img = stitch_img.merge(tile, 'vertical', 0, -y, mblend =blend)    
22.         else :
23.             stitch_img=tile
24.     print (stitch_img.width,stitch_img.height,"width","height")        
25.     stitch_img.dzsave('test_80X80')

I have tried inserting tile=tile.globalbalance() at line number 19 for adjacent contrast adjustment , and also stitch_img=stitch_img.globalbalance() at line number 22 for contrast adjustment between each row. It's not working and I am getting an error.

Error:

raise Error('unable to call {0}'.format(operation_name))
pyvips.error.Error: unable to call globalbalance
im_global_balance: unable to open "temp-0"

Please provide an example for this function.

from pyvips.

Don't use black, it'll get confused.

You need to start from a set of images on disc, merge them together, then call globalbalance.

from pyvips.

How those black pixels can be ignored. I have added 255 value to those pixels but it's not working with global balance. I can't remove those black pixel area, however, I can modify them to work for global balance. What kind of modification is needed for global balance?

from pyvips.

You don't need black to assemble a mosaic, do you? Build it without using black and globalbalance should work.

from pyvips.

Whenever I am using merge function, I will have some black pixels because my image is shifting in vertical direction also. So, an extra region is padded with a black pixel. I was using a black image for the first merging operation to make coordinates easy otherwise I have to make dynamic coordinates for merging operation, which is related to the input frame of reference.

from pyvips.