RAW capture

Greg,

Thanks for the information on RAW capture....definitely worth more than 2 cents! I've never been good at the math part of digital photography...my knowledge is purely experiential. Many years of Zone system shooting, printing, and plotting film curves.

The potential benefit you cite for RAW images, the bit depth, turns out to be an illusion. Although many RAW files contain 12 bits/channel, it's in a linear space rather than the gamma response space of JPEG or 24-bit TIFF, and doesn't actually encompass a greater dynamic range. (See my page at <http://www.anyhere.com/gward/hdrenc/> and scroll down to "What Is a Gamma Encoding?" to more.) Since the camera and the A/D converter inside the camera are both linear devices, this is in fact why 12 bits is necessary for an 8-bit gamma-encoded output. Otherwise, you'd end up with horribly visible quantization errors (banding) at the bottom end.

I also expect this is why CS2 is inferior in assembling HDRs to Photosphere. I recently ran a test with the same set of 5 panos...and the CS2 image was noticeably contrastier, with banding in the extreme ends of the exposure. Also the .hdr file size was 4 MB smaller than the one generated in your app.

It's taken me many months of trial and error...but I've finally got an all OSX work flow that's reliable and repeatable.

I capture 5 or more exposures at each of 6 positions around, using a Nikon 5700 with FC-E9 full spherical fisheye. I crop and de-warp images in Photoshop (using a custom plug-in), then stitch in Stitcher 4 (now 5), then put back the missing EXIF data and do the finally assembly in Photosphere.

Anyone else have experience using a non-SLR digital camera for HDR capture?

Lisa

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Hi Lisa,

What I've noticed in Photoshop CS2's "Merge to HDR" function is that they try to preserve some of the "character" of the original image. To do this, they would have to maintain the camera's tone curve, which is impossible if your goal is to obtain a scene-referred HDR result. In other words, they set conflicting goals for their process, and the result is something that satisfies neither goal very well.

I do HDR captures with my Olympus 4040 all the time, but I don't attempt to do stitching. The biggest problem with non-SLR cameras is that they tend to suffer much more from lens flare, since their optics are not up to 35 mm standards.

-Greg

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From: "L.Yimm" <[email protected]>
Date: January 25, 2006 12:29:15 PM PST
...
I also expect this is why CS2 is inferior in assembling HDRs to Photosphere. I recently ran a test with the same set of 5 panos...and the CS2 image was noticeably contrastier, with banding in the extreme ends of the exposure. Also the .hdr file size was 4 MB smaller than the one generated in your app.

It's taken me many months of trial and error...but I've finally got an all OSX work flow that's reliable and repeatable.

I capture 5 or more exposures at each of 6 positions around, using a Nikon 5700 with FC-E9 full spherical fisheye. I crop and de-warp images in Photoshop (using a custom plug-in), then stitch in Stitcher 4 (now 5), then put back the missing EXIF data and do the finally assembly in Photosphere.

Anyone else have experience using a non-SLR digital camera for HDR capture?

Lisa

I don`t know wether this is the same, but I`ve used a Nikon 5000 and what I did was to convert everything to rad format first using HDRgen, and then crop with pcompos (this could also do the stitch) I was not de-warping though, but doing like this I could do everything in a script .
Maybe pcomb could do the de-warping in several steps to limit the -y displacements...? don`t know if it`s possible at all
my cent and a half :slight_smile: hope it makes sense

Santiago

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On Jan 26, 2006, at 5:29 AM, L.Yimm wrote:

I capture 5 or more exposures at each of 6 positions around, using a Nikon 5700 with FC-E9 full spherical fisheye. I crop and de-warp images in Photoshop (using a custom plug-in), then stitch in Stitcher 4 (now 5), then put back the missing EXIF data and do the finally assembly in Photosphere.

Anyone else have experience using a non-SLR digital camera for HDR capture?

Unfortunately, Photoshop is not trying to preserve anything from the
original image. It's trying to get everything linear and do the merge.
BUT there are some problems with the current code.

And, of course, Photoshop is color managed - so if your display profile is
out of whack, images will look bad in Photoshop.

Chris

···

On 1/25/06 2:37 PM, "Gregory J. Ward" <[email protected]> wrote:

Hi Lisa,

What I've noticed in Photoshop CS2's "Merge to HDR" function is that
they try to preserve some of the "character" of the original image.
To do this, they would have to maintain the camera's tone curve,
which is impossible if your goal is to obtain a scene-referred HDR
result. In other words, they set conflicting goals for their process,
and the result is something that satisfies neither goal very well.

I do HDR captures with my Olympus 4040 all the time, but I don't
attempt to do stitching. The biggest problem with non-SLR cameras is
that they tend to suffer much more from lens flare, since their
optics are not up to 35 mm standards.

-Greg

From: "L.Yimm" <[email protected]>
Date: January 25, 2006 12:29:15 PM PST
...
I also expect this is why CS2 is inferior in assembling HDRs to
Photosphere. I recently ran a test with the same set of 5
panos...and the CS2 image was noticeably contrastier, with banding
in the extreme ends of the exposure. Also the .hdr file size was
4 MB smaller than the one generated in your app.

It's taken me many months of trial and error...but I've finally got
an all OSX work flow that's reliable and repeatable.

I capture 5 or more exposures at each of 6 positions around, using
a Nikon 5700 with FC-E9 full spherical fisheye. I crop and de-warp
images in Photoshop (using a custom plug-in), then stitch in
Stitcher 4 (now 5), then put back the missing EXIF data and do the
finally assembly in Photosphere.

Anyone else have experience using a non-SLR digital camera for HDR
capture?

Lisa

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Thanks for the feedback Chris. My display profile is good. We did this on 2 different machines to make sure it wasn't just us seeing things.

Lisa

···

On Wednesday, January 25, 2006, at 07:13PM, Chris Cox <[email protected]> wrote:

Unfortunately, Photoshop is not trying to preserve anything from the
original image. It's trying to get everything linear and do the merge.
BUT there are some problems with the current code.

And, of course, Photoshop is color managed - so if your display profile is
out of whack, images will look bad in Photoshop.

Chris