Gear Talk > EOS Bodies - For Stills
What is "highlight tone priority" good for anyway?
Marsu42:
I don't know if this is implemented in more expensive bodies than my 60d - but htp doubles the iso and applies a non-linear curve so that highlights get more resolution while the shadows are compressed. In good light, I used to use it all the time at the beginning ("why not?"), but then discovered that the darks get so little resolution that raising them in postprocessing introduces noise or banding.
Nowadays, I'm using it on shots that have very bright highlights that I don't want to blow - like an animal's fur with the sun behind it or white flowers when shooting a macro of an insect on them. I've read some about htp elsewhere, but I have to admit the only people with a clue seem to be around here... thus the questions:
* Why does htp raise the iso value - does htp increase dynamic range (it doesn't exchange the sensor behind your back...)? Or is it just a convenience that saves you heavy underexposing and thus you are able to see the result on the camera screen and not only later after postprocessing?
* Do you use htp at all? If yes, what for?
I'm wondering because htp is the only camera gimmick that is applied to raw, too - so it might be something to it after all...
Bosman:
--- Quote from: Marsu42 on April 15, 2012, 07:12:29 AM ---I don't know if this is implemented in more expensive bodies than my 60d - but htp doubles the iso and applies a non-linear curve so that highlights get more resolution while the shadows are compressed. In good light, I used to use it all the time at the beginning ("why not?"), but then discovered that the darks get so little resolution that raising them in postprocessing introduces noise or banding.
Nowadays, I'm using it on shots that have very bright highlights that I don't want to blow - like an animal's fur with the sun behind it or white flowers when shooting a macro of an insect on them. I've read some about htp elsewhere, but I have to admit the only people with a clue seem to be around here... thus the questions:
* Why does htp raise the iso value - does htp increase dynamic range (it doesn't exchange the sensor behind your back...)? Or is it just a convenience that saves you heavy underexposing and thus you are able to see the result on the camera screen and not only later after postprocessing?
* Do you use htp at all? If yes, what for?
I'm wondering because htp is the only camera gimmick that is applied to raw, too - so it might be something to it after all...
--- End quote ---
I recommend doing the research in Google. If you need more look it up. To sum it up, you lose info in shadow details and lose the use of iso's lower than 200. You gain more info in highlight detail with the setting on. The info is embedded in raw and jpg. This is something you can do in post if needed. Essentially Chuck Westfall from Canon says it is a Curve applied in camera rather than in photoshop. I have tried using it but don't like adding limitations to my camera and i do my best to get proper exposures when i shoot. All that said it does work and makes me consider the idea of using it if my output on a super sunny day could use some help.
http://www.imaging-resource.com/PRODS/E1DMK3/E1DMK3EXPOSURE_HTPMODE.HTM
http://digitalprotalk.blogspot.com/2007/10/highlight-tone-priority-image-salvation.html
Marsu42:
--- Quote from: Bosman on April 15, 2012, 11:47:10 AM ---I recommend doing the research in Google. If you need more look it up.
--- End quote ---
I already knew and wrote what htp does, I've taken tenth of thousands of pictures with it. And I'm perfectly able to type something into google, but as you may or may not have discovered that not everything an internet search returns is very reliable. So I guessed it'd do no harm asking here if anyone has separated the usual user theories from the real information, no need for anybody to reply...
That being said, thanks for the links. But my question still is: If it's just an in-camera tone curve, why does it raise the iso value? Is it really 100% something that can be done in postprocessing?
Mt Spokane Photography:
--- Quote from: Marsu42 on April 15, 2012, 12:12:34 PM ---
--- Quote from: Bosman on April 15, 2012, 11:47:10 AM ---I recommend doing the research in Google. If you need more look it up.
--- End quote ---
I already knew and wrote what htp does, I've taken tenth of thousands of pictures with it. And I'm perfectly able to type something into google, but as you may or may not have discovered that not everything an internet search returns is very reliable. So I guessed it'd do no harm asking here if anyone has separated the usual user theories from the real information, no need for anybody to reply...
That being said, thanks for the links. But my question still is: If it's just an in-camera tone curve, why does it raise the iso value? Is it really 100% something that can be done in postprocessing?
--- End quote ---
If you use jpeg and send your images electronically straight to be published, or printed, it is useful. While I normally use raw and post process, many users have valid reasons to use jpeg and it will certainly improve shadows in images where I use jpeg for straight to the printer applications.
The setting is usually not used by raw processors except for DPP, so it has no effect on raw images for most photographers. Its just a trigger telling DPP to apply a exposure curve to the raw image as it processes it, no harm done, you can change the curve any way you like.
Marsu42:
--- Quote from: Mt Spokane Photography on April 15, 2012, 12:30:02 PM ---The setting is usually not used by raw processors except for DPP, so it has no effect on raw images for most photographers. Its just a trigger telling DPP to apply a exposure curve to the raw image as it processes it, no harm done, you can change the curve any way you like.
--- End quote ---
This is interesting and unexpected (and still doesn't explain the raised iso) because Adobe raw in Lightroom does the same thing. I really expected that htp alters the actual raw data, too. It might be futile to ask but are you 100% sure about this? Any sources?
Navigation
[0] Message Index
[#] Next page
Go to full version