Panoramic image retouching
For now I just have one example to walk through with you. The panorama of the kitchen of the house I was renting in Croydon is a nice picture. However, when I first stitched this I got a mess around the back door caused by dramatic contrast change. Below is the "before" and "after" of the door.
The trick here is that I was able to correct the blending that PhotoVista Panorama employed. After doing the first stitch, I re-stitched the image after manually changing the stitching points around the door. In fact I completely separated the door image from those around it and then de-selected the "automatically align images" option. Here's what I then had:
|The three images around the doorway - note the contrast change|
Why is this useful? Well, PhotoVista has warped all the images ready to blend them together, however I have forced the images apart. So now I can remove part of the image either side of the door and paste it into the final image. Basically the centre (dark) image is pretty useless, so I want to use more of the images on either side.
To select the area to one side of the door, I use Adobe Photoshop and use the QuickMask tool (which is to the right of the Standard Mode Mask (see illustration left)).
I don't just want to select a square shaped area, rather on the edge nearest the door I want a softened edge so that the pasted area will fade nicely into the darker door area. I can achieve this in QuickMask mode using the Gradient tool () to 'paint' the mask. If you haven't tried doing this try it and you'll see what I mean. After painting the mask I get:
|Using quickmask in PhotoShop to define a feathered selection|
Now I can switch back to Standard mode and by making a subtraction from the mask area (by holding down the ALT key) I can finalise the area I want to copy:
|A piece of the feathered mask ready for compositing|
Now all I have to do is paste this into the stitch that PhotoVista created, position it correctly and hey presto the image is much cleaner. I used a separate layer for the pasted areas of the image and here's the actual section of the final panorama that was replaced in the touched-up version. You can clearly see how it fades away into left-to-right which is why there is no seam line showing in the final image.
|The final components used to composite with the stitched image to retouch stitching problems|