HDR Stack 4 scenes.

[Piotr Krochmal]

I had to make photo of room wide big room. I had only 12 LED lamps so I make it partially. Place by place. I've ended with 40 shots (4 sets of lights x 10 exposure bracketing).

And there is my story.

What I need to get is ofc 1 photo combined. For compression I use SNS-HDR so I need to get EXR file.

Zero step is in Capture one -> DNG -> TIFF is ok with all metadata.

1. step 10 x tiff -> HDR stack -> Done - properly aligned  ended with 4x EXR files.

2. step 4x EXR files -> STACK -> Failed affinity cannot properly aligned photos.

I've tried stack all 40 photos and have been properly aligned but it not give me proper (HDR) exposure.

Help I have more photos to combine

In attachment JPGs of each scene to aligned

[John Rostron]

Have I got this right?

In Step 1, you have 10 images with identical lighting but with different exposures. You then merge these using a HDR merge stack. This is repeated for each of the four lighting regimes, and each is exported as a 32-bit EXR file.

In Step 2, you load the four EXR files into a stack and they will not properly align. 

Is there any reason for using ten exposures? What was the EV spacing for these?

What do you intend to do with the stack once it is aligned? Take a mean, median, or what?

Have you tried loading the four files into as layers (copy, paste) and then aligning manually? They look pretty close by eye.

John

[John Rostron]

I have just download your four images posted here and loaded them into a stack with no problem. I used the minimum option to get rid of the excess violet light. It does, however, include the leg of what looks like a music stand at the bottom right.

It could be that Affinity does not like to load EXR files into a stack. Have you tried exporting your HDR files as tiffs (16-bit or 32-bit) and then trying to load those into a stack?

John

[Piotr Krochmal]

Hi, JPG are only for showing "what is going on" photos :).

Sorry if I'm writing not clear :).

Step One is 10x TIFF (prophoto 16bit no compression (205MB per file).

I use 10 to have better tonality and less noise. I don't have problem with stacking, only with aligning.

to clarify: I have 40 TIFF 16bit ProPhoto color space.

1. Stacking them all together give me properly aligned photo

2. Stacking in groups in HDR to EXR file work flawlessly.

3. Stacking EXR or TIFF after 2. don't work

I've tried to copy EXIF data from source using exiftool  (it warning about bad exif) but it not help

Best

[Piotr Krochmal]

On 10/26/2018 at 3:15 PM, John Rostron said:

Have you tried loading the four files into as layers (copy, paste) and then aligning manually? They look pretty close by eye.

John

I will not do that, this is why I have software for

[Piotr Krochmal]

So no support in that case?

[John Rostron]

On 10/27/2018 at 2:20 PM, Piotr Krochmal said:

I've tried to copy EXIF data from source using exiftool  (it warning about bad exif) but it not help

Try exporting as16-bit tiffs, and under More, make sure that metadata is not  included. This should remove exif data. Then try loading the four tiffs into a stack.

On 10/26/2018 at 10:19 AM, Piotr Krochmal said:

I've tried stack all 40 photos and have been properly aligned but it not give me proper (HDR) exposure.

What do you mean by not the proper (HDR) exposure? Could you post a jpg version of this 40-file result? 

HDR algorithms assume that the contributing images each have different exposures. (You still have not told us what EV spacing you used.) It could be that the reason for the 40-file failure is because of these EV overlaps

John.

[All Media Lab]

Hi Piotr,

The size of your example images is not the same! I had a look in Photomatix.

1. 1000px X 668px

2. 1000px X 667px

3. 1000px X 666px

4. 1000px X 666px

To me your images look like they have the same exposure time, but different lightning with LEDS on different spots of the total space. That has nothing to do with HDR. If this is the end result of the total HDR proces you have to take in account that merging 4x the end result of 4 HDR images will not give you a nice HDR image.  Or do you have more images to try? I have been reading 10 exposure bracketing? In a situation like this 3x to max 5x bracketing will be more then sufficient. 

Regards,

David

 

[John Rostron]

38 minutes ago, All Media Lab said:

Hi Piotr,

The size of your example images is not the same! I had a look in Photomatix.

1. 1000px X 668px

2. 1000px X 667px

3. 1000px X 666px

4. 1000px X 666px

To me your images look like they have the same exposure time, but different lightning with LEDS on different spots of the total space. That has nothing to do with HDR. Or do you have more images to try? I have been reading 10 exposure bracketing? In a situation like this 3x to max 5x bracketing will be more then sufficient. 

Regards,

David

 

Yes, these are my thoughts. 10 shots does seem like overkill.

I wonder if an alternative approach might be appropriate:

• Take the four maximally exposed images (one from each lighting scenario).
• Load these into a stack and merge. The blending mode is up to you, but I found that minimum gave the best results.
• Flatten the stack and export as a 16-bit tiff.

Repeat this for quartets with lesser exposures (ten if you insist, but five would do).

Load these five (or ten) files into an HDR stack and merge.

John

[Piotr Krochmal]

1 hour ago, John Rostron said:

Yes, these are my thoughts. 10 shots does seem like overkill.

I wonder if an alternative approach might be appropriate:

• Take the four maximally exposed images (one from each lighting scenario).
• Load these into a stack and merge. The blending mode is up to you, but I found that minimum gave the best results.
• Flatten the stack and export as a 16-bit tiff.

Repeat this for quartets with lesser exposures (ten if you insist, but five would do).

Load these five (or ten) files into an HDR stack and merge.

John

Thanks John but know why I take 2x5 bracketing it is not an issue.

IMHO Mean is best blending option but there are so many types that it depend of type

Issue is that when I stack all 40 TIFF they were aligned perfectly. but when I do it in two step 4x10 per HDR then 4x1 EXR aligning is not working I've tried both type of aligning.

is there any DEV who wrote that part of code?

[Piotr Krochmal]

Thanks All Media Lab, for clue with different size of jpg. And time spended to check files.

After many trials and errors (including over 1h save of stack of 40 pictures for export stacket files paritaly)

I found brazenly straight solution.

4x 10xTIFF stack to HDR  Without aligning.  As camera almost not move at every shots it give good end product.

As all 4 EXR had exact size they merge with aligment  very nicely. So it was not EXIF inducted. still exif is unproper but hey I've got what I need.

And back to bracketing.  LED RGB lights (GRB Amber in my case) are not as easy to work with. monochromatic light source ultra easy blow RGGB subpixels of sensor. 10 exposure bracketing is also for noise reduction (K1 allow you to 5 auto bracketing so I just shit exposure compensation -2/3ev after first burst. It work very well. What limit me now is 14bit RAW. Still combining 40 ISO 100 RAW give you noise as low as ISO 100/40 = 2,5.

So how it ended? Below 50% 50% export (size and quality) and 100% 100% crop.

[All Media Lab]

Hi Piotr,

Looking at the end result you can see that merging 4 HDR's give a very dark result and loss of spaciousness. If possible I would go for max 5 x bracketing of the space (low iso small diaphragm) with light, but without any lighting effect. Then take 4 images of the lighting effects somehow extract them from the background and put on top. (much work and difficult to achieve). 

Easy way to do it is: imitate the light effects in Affinity (tutorial! Only have to choose the color purple and add the effects on the spots that need it, preferable on different layers.) and put them on top of the only one HDR.

Advantage: Much simpler workflow, best HDR you can get, no buildup of noise and other artifacts, fare more sharpness. I'm a big fan of Affinity, but for HDR I use Photomatix .

Regards,

David

[Piotr Krochmal]

Hi David thanks for you thoughts.

For HDR I've tried also Photomatrix but SNS-HDR give always most natural compression.

You can't simulate 3D light with 2D light. there are not for color only but for "bumpmap".

Darknes is intended and made in post in C1 + NIK

Best

 

[John Rostron]

I admit that I had difficulty in trying to comprehend exactly what you were aiming for. However, I am pleased that you now seem to have it resolved to your satisfaction. It is a pity that none of the Affinity staff saw fit to comment.

John