APP does not export what it shows in the preview

[rhadorn]

APP does not export what it shows in the preview

by rhadorn » Wed Mar 31, 2010 4:16 pm

My stitched image: 21 bracketed shots (63 images). Dynamic range handled in HDR PhotoStudio, saved as exr files.
Stitched the 21 exr files in APP, exported the result in TIFF.

Problem: the image saved from APP has a much higher global contrast between sky and ground than the image shown in the preview (see screenshots below).

I tried several gamma settings in Levels, without any success: the image saved remains unchanged.

During the computation of the result, the small preview shows bits of the image in various brightnesses before it settles on what becomes the final image.

Did anybody have the same symptoms? Which is the medicine?

Reto

[mediavets]

by mediavets » Wed Mar 31, 2010 4:58 pm

Which is the medicine?

Reto

Process your HDR image sets to TIFF or JPEG prior to stitching.

[GURL]

by GURL » Wed Mar 31, 2010 6:23 pm

Problem: the image saved from APP has a much higher global contrast between sky and ground than the image shown in the preview (see screenshots below).

Blending of the preview is different from default blending for the final rendering. If you are pleased with the preview you should select Multiband rather than Smartblend and then the rendered pano will be identical.

Hopefully, in a future version the same options will be available for both. Before that, using the smallest size percentage for rendering can be used as a work-around to preview the final pano (this is much faster than a 100% rendering.)

[rhadorn]

by rhadorn » Wed Mar 31, 2010 8:44 pm

Thank you both for your help.

Well... exr is included in the list of formats APP can read, and so it does; consequently, I expect that the program can also edit the image.

Since the full list of formats is from XnView, I tried to convert the files in that program. For that, I had to download the appropriate plugin and once the latte was installed... I got a message concerning a missing MSVCR71.dll. I looked for it, downloaded and put it into the System32 directory it without any effect.

So I downloaded the full set of plugins, hoping the setup would also install the dll in a correct manner: no effect.

So I was happy to read the second recommendation: to use the multiband blending method rather than the smartblend one. I regret to say that the result is strictly the same as with smartblend. I do not understand why none of the editing possibilities in APP has any effect on the image.

I am using APP 64 bits V2.0.6 on a Windows 7 system.

Reto

[Mr Moose]

by Mr Moose » Wed Mar 31, 2010 9:21 pm

When sending HDR files to APP I've found that they need to be in sRGB color space, other wise the colors that APP renders are not the same. I can't remember but you also might have to turn off color correction in APP as well.
Anyone else find this to be the case? Is this correct, or, am I doing something wrong?

[hankkarl]

by hankkarl » Wed Mar 31, 2010 10:16 pm

Have you tried tonemapping the rendered image?

Also, before you tonemap, use PS to tag the colorspace back to whatever it started from -- APP strips off the colorspace tag. If you view a photo without a colorspace tag, it defaults to sRGB on most systems, so if you used prophoto on the input, and APP strips the colorspace tag, it will look wrong until you add the the colorspace tag to the image.

[AlexandreJ]

by AlexandreJ » Thu Apr 01, 2010 10:43 am

When doing HDR in autopano, the editor applies an automatic tonemapper on the image to be able tot display every tone : that's why you have this washed look in the editor.
Of course when rendering, you don't need that when doing HDR / EXR format. It's disabled. So you have the real dynamic ( you should need to tonemap it too to display every tone of the picture ).

[rhadorn]

by rhadorn » Thu Apr 01, 2010 8:02 pm

Thanks all for your support. I came to a solution - actually, several solutions. The best idea is probably to give APP OpenEXR files and save the result as HDR, and then to tonemap in a dedicated program. My main difficulty was to understand that APP, although being HDR compatible, would not make any tonemapping.

The direct way (feeding APP with CR2 files did not work because some of those files bear too little information to be stitched effectively (overexposed sky with very little ground). I will give it a try again while exluding those files. Another reason not to go the direct way is the correction of chromatical aberrations.

Another difficulty relates to the subject. As already mentioned, the 3 lines by 7 columns picture includes big surfaces of an overcast sky. If I merge and tonemap the bracketed shots before stitching the result in APP, then the shots of the sky are fairly dark (say a deep middle grey) because the underexposed shot is the only usable one. The color correction of APP does very well at compensating for that.

Reto