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Old 08-18-2014, 01:53 AM   #1
unclebob
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can the samsung HDR camera mode be used for HDRI?

my kid bought me a Samsung S5, the camera has an HDR mode. now I am a dunce when it come to such things, so could an image taken in HDR be used for HDRI render?

if not, is there or what is a difference between HDR and HDRI?
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Old 08-18-2014, 02:27 AM   #2
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The HDR picture taken by your S5 is a post-processed image with some hdr look & feel (avoiding too bright zones and such things) but in the end it is a LowDR image, a JPG.

An HDRI it's a 32bit full float picture with all the light information on it so you can identify the light sources for example (wich is what render engines do to sample them), it can't be a JPG picture, it usually is a .HDR or a .EXR.

Hope this clarifies this a bit.

Cheers.
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Old 08-28-2014, 08:08 AM   #3
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A bit late with my reply, but as CerberusC said the final image is an LDR (Low Dynamic Range) image. The S5 does take multtiple images, but then combines them (I believe 3), to a temporary 32-bit HDR (High Dynamic Range) image, but then tonemaps it down to a 8-bit LDR jpg file. But I don't believe you can save a 32-bit HDR from the camera, but you might be able to with a seperate app. Also HDRI just means High Dynamic Range (Image), and can mean any type of image, although a lot of people use it as a general term for HDR reflection maps or HDR panoramas. Do you really need a HDR file? It depends on your application and needs. If you're just taking pictures for fun, or you want a picture with that HDR stylized look, or you don't need a linear workflow, then just having the tonemapped image is fine. If you're doing composting or are trying to make high resolution panoramas, then you would want a HDR file such as an hdr, exr, or a 32-bit tiff. Which if that's the case I would recommend using a decent quality camera, such as a DSLR. Also, as CerberusC said, if you're using the images for lighting and reflections in 3d renderings, and you want good accuracy, then you would want to use HDR files, but depending on the scene, you can get away with tonemapped or just regular photos.

Some further reading -
HDR - http://en.wikipedia.org/wiki/High-dynamic-range_imaging
HDR Rendering - http://en.wikipedia.org/wiki/High-d...range_rendering
Tone Mapping - http://en.wikipedia.org/wiki/Tone_mapping
RAW (Medium Dynamic Range Images) - http://en.wikipedia.org/wiki/Raw_image_format
The HDRI Handbook - http://www.hdrlabs.com/book/index.html
HDRLabs - http://www.hdrlabs.com/news/index.php

Last edited by Ian31R : 08-28-2014 at 08:43 AM.
 
Old 08-29-2014, 12:33 AM   #4
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Thank you Ian for the reply and detailed answer. I've played around with it since my post, one of the things the HDR mode does it help to lighten a dark scene to make it more presentable without flash.
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Old 08-29-2014, 04:30 PM   #5
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Sure, glad to help. If I may ask, what where you planning on using the hdr mode for? You mentioned HDR rendering, do you mean for 3D renderings?
 
Old 08-29-2014, 10:38 PM   #6
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yes for 3D rendering in Cinema4D
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Old 08-30-2014, 05:41 AM   #7
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Oh ok, but how do you plan on applying the HDR images to your 3d scenes? Just as background images, for textures, or for environment maps / panoramas? HDR for the background plates can be helpful, but aren't always needed, usually you can get away with processing RAW photos and converting them to 16-tiffs. The same for textures, For HDR environment maps, if you're planning on using the S5 for stitching a fully spherical HDR image you might run into problems. All of the panorama modes I've used on phones never really work very well. Also with the S5, I believe you have to either choose panorama or HDR mode, you can't do both. Also I think the panorama mode on the S5 only lets you create a panorama from a horizontal strip of images, so you can't create a fully spherical panorama. Again, you might be able to find alternative apps for that. Although you could get a mirrored ball and use this technique in HDR mode and stitch the shots together in an external program to create an environment map.


I tried finding apps where you might be able to save an original HDR file, but most HDR apps that I've found don't specify that. Although HDR Camera does say that you can save the captured exposures, so you can merge them to an HDR file using programs such as Photoshop, Photomatix, or Picturenaut. Also Camera HDR Studio and Pro HDR Camera for Android might have that functionality as well, I'm not 100% certain though, but they do seem to have tons of features.

Last edited by Ian31R : 08-30-2014 at 05:50 AM.
 
Old 08-30-2014, 05:22 PM   #8
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Thanks again Ian. Yes it would be for environmental maps and now that you've expanded the topic further I can see it most likely not work oh well it isn't the end of the world, I was just hoping.
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Old 08-30-2014, 09:05 PM   #9
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Well I don't know if I would say using a mobile device for environment maps is hopeless. From my experience I just haven't had any success with it, but then again I haven't tried every app out there, and I haven't tried to use a ton of different devices.

In general though making panoramas and environment maps can be an involved process, from the setup, to the capture, to the processing and stitching. Even the chrome ball technique, which you can get away with just two shots to make the environment map can require work, but that's just like a lot of things in CG and in life in general.

If you still want to use your phone, I would try to work with a chrome ball, and try to experiment with other HDR apps. Using a chrome ball is an inexpensive way to practice and is a good starting point for getting into environment maps.
 
Old 08-31-2014, 12:35 AM   #10
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It will be much easier shooting real HDR's with the upcoming Android 5.0 release which features full RAW support so you can utilize the whole dynamic range of the sensor.

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Old 08-31-2014, 12:46 AM   #11
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Quote:
Originally Posted by Magnus3D
It will be much easier shooting real HDR's with the upcoming Android 5.0 release which features full RAW support so you can utilize the whole dynamic range of the sensor.

/ Magnus



In the meantime, you can still get perfectly acceptable results using an LDR image as an environment/reflection/lighting map.
 
Old 09-01-2014, 12:57 AM   #12
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Quote:
Originally Posted by musashidan
In the meantime, you can still get perfectly acceptable results using an LDR image as an environment/reflection/lighting map.


Definitely, as long as your environment doesn't have too much contrast where elements are too over / under exposed or are totally clamped. That's why its usually a good idea to use a light meter or take a few test shots and check out the image's histogram. But yeah I used to use a chrome ball to capture environments without using any HDR, and the results were pretty decent.

Quote:
Originally Posted by Magnus3D
It will be much easier shooting real HDR's with the upcoming Android 5.0 release which features full RAW support so you can utilize the whole dynamic range of the sensor.


Interesting, didn't here about that. I wonder how wide the range would be on a phone like the S5. It can vary from camera to camera, some are around 14-bits, and some are just 12. In general its good to have any increase in dynamic range. Depending on the environment, such as an overcast sky, you can capture the whole range of a low constrast scene from just a single raw image.
 
Old 09-01-2014, 01:40 PM   #13
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The dynamic range is not a huge issue, although it can be somewhat limited in the small cellphone sensors we have today. It's probably comparable to 12bit. They had to cap the dataflow atleast a couple of years ago since they processingpower of cellphone's were not anywhere near what we have today with quadcore and octacore cpu's plus 64bit.

As the new Android 5 will support fully manual exposure just like the Nokia Lumia 1020 does it will be much easier to capture multiple differently exposed shots and then compile those together into one final HDR, and for a panorama you just have to shoot several differently exposed shots in a spherical way around your centerpoint and then stitch those together in your PC.

/ Magnus
 
Old 09-01-2014, 06:28 PM   #14
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Interesting, it would make sense that a smaller camera sensor would have a lower range. But hopefully it will be higher also as more and more phones are now having quad core cpus.

Manual exposure is nice, since with shooting panoramas you pretty much need everything on manual. The problem is though, as I said before, stitching on phones never seems that reliable. It might be due to the fact that you need to rotate the camera around a centerpoint or nodal point to avoid parallaxing. So you would need a tripod and panoramic head to get a clean stitch.
 
Old 09-02-2014, 08:50 AM   #15
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You are way better off stitching your panoramas on your computer instead of on the phone, the computations required are quite massive and there are no real good applications for that on a mobile device so do it on a real computer for now. And always make sure you shoot on a tripod of some sort so you get a fixed nodalpoint and a locked exposure and all that to avoid problems.

/ Magnus
 
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