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Pre vs. Post SNS HDR processing

PostPosted: Thu Sep 06, 2012 1:12 pm
by markdfink
Hi,

I do a lot of stitching with PTGui, both for VR and mosaic images for print. Sometimes, my mosaics are far too large for SNS HDR to handle with the amount of memory that I have. So, last night, I did a test.

1. I stitched a reduced size image in PTGui, outputting the Blend Planes, that is, one TIFF file for each exposure level.
2. I brought those images into SNS HDR and adjusted the parameters to get what I wanted.
3. I saved those parameters as a new preset.
4. I returned to the original unstitched files and manually applied the new preset to each one, giving me four new source images with SNS HDR already applied.
5. I brought those new source images into my existing PTGui project so that it would stitch identically and created a new image the same size as in #1.
6. I opened both images in Photoshop and layered them on top of each other, setting the blend mode of the top layer to Difference.

I expected to see no difference between the two, but there was a noticeable difference. Actually, I could see it just looking at the images side by side, but the Difference layer shows it more clearly. I've attached a screen shot of that.

Am I wrong in thinking that using the same preset in SNS HDR either before on the source images, or after on the stitched images, should yield the same results?

Thanks,

Mark

Re: Pre vs. Post SNS HDR processing

PostPosted: Thu Sep 06, 2012 1:20 pm
by Sebastian Nibisz
markdfink wrote:Am I wrong in thinking that using the same preset in SNS HDR either before on the source images, or after on the stitched images, should yield the same results?

The results will not be identical but will be very similar.