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Thread: I'm still not convinced...

  1. #1

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    I'm still not convinced...

    Highlight Tone Priority.

    HTP is supposed to reduce exposure then push the shadows in processing. Well, I've had a brief play at lunchtime and it's still left me wondering. I did shoot three images with it on and some with it off against a severly afflicted scene lighting-wise (dark interior and bright daylight through the window) It certainly brought up the shadows to at least a full stop over a 'normal, expose for the highlight' frame withought blowing the highlights.

    What I'm not convinced about is this: is the sensor adjusting to the scene on a per pixel basis as some models can on white balance in full auto or just moving the whole histogram to the right in relation to the exposure?

    If it's the latter then it's just what we do anyway (jpeg shooters) but if it's the former which I suspect it might be judging by the shadows then it is of real, practical use. I'll have the camera on 'P' for professional at the next wedding then ...

    Any tecchies around here with in depth knowledge they'd like to share?

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    Re: I'm still not convinced...

    Quote Originally Posted by SteveF View Post
    Any tecchies around here with in depth knowledge they'd like to share?
    I'm not even close to being a techie and I'd never heard of highlight tone priority so I ran a Google search on the term. This was the first hit:
    http://shootintheshot.joshsilfen.com...-canons-dslrs/

    Hope it helps.

    Ken

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    RustBeltRaw's Avatar
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    Re: I'm still not convinced...

    Highlight tone priority is an in-camera post-processing technique. As far as I know, activating it doesn't affect anything prior to or during the shutter press, but my understanding from my 60D's manual is that it brings down the highlights a bit in an attempt to preserve mid-tone detail. This video by Rabble-House Productions has a good overview with some real-world examples. Note that HTP seems especially effective in combating reflected highlights.

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    Re: I'm still not convinced...

    Thanks for your responses. Looking at it afresh just now it's certainly the better option to use HTP first then photoshop later in the majority of cases.

    Must spend some time this weekend testing this if ever the sun makes an appearance in good old Blighty.

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    Re: I'm still not convinced...

    HTP is software executed, and only affects the Jpg files, not the RAW. It has the same effect as adjusting the shadows/highlights sliders or the highlights recovery slider in PS or LR, but you have no control on the amount of adjustment.

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    Re: I'm still not convinced...

    Looking at it afresh just now it's certainly the better option to use HTP first then photoshop later in the majority of cases.
    I'd say the reverse. The link in the first response explains it well. I would rather have the unaldulterated raw data, and I have never used HTP. If dynamic range is too great and you have a static image, you might want to try exposure fusion with multiple images.

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    William W's Avatar
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    Re: I'm still not convinced...

    Quote Originally Posted by SteveF View Post
    Highlight Tone Priority. . .is supposed to reduce exposure then push the shadows in processing. Well, I've had a brief play at lunchtime and it's still left me wondering. I did shoot three images with it on and some with it off against a severly afflicted scene lighting-wise (dark interior and bright daylight through the window) It certainly brought up the shadows to at least a full stop over a 'normal, expose for the highlight' frame withought blowing the highlights. etc . . .

    If it's the latter then it's just what we do anyway (jpeg shooters) but if it's the former which I suspect it might be judging by the shadows then it is of real, practical use. I'll have the camera on 'P' for professional at the next wedding then ...

    Any tecchies around here with in depth knowledge they'd like to share?
    The following comment is in respect of Canon DLSR Cameras and based upon my observations and it is a synopsis of my hypothesis of HTP functionality.

    *

    I conclude that HTP does affect the raw file.

    It occurs to me that if HTP enabled the camera underexposes by (about) 1 stop. This logically seems to be done by lowering the ISO.

    This lowing of the ISO, might be akin to how the camera actions the selection of the “intermediate” ISO, such as: ISO 500 & ISO 640; ISO 125 & ISO320 etc.

    This data IS recorded to the RAW file.

    *

    In-Camera JPEG conversion:

    When the camera generates the JPEG file it occurs to me that the HTP flag is noted and a curve is applied to boost the shadows and mid-tones without affecting the highlights. HTP is useful for shooting JPEGS, to achieve this effect, SOOC.

    *

    Post Production Programmes:

    It occurs to me that when (most) Adobe Products see the HTP flag they automatically boost the exposure slider by one stop.

    It occurs to me that Canon DPP manages HTP, slightly differently. When DPP sees the HTP flag set on the underexposed RAW file, it applies a different curve in the RAW conversion which again will selectively boost the shadows and mid-tones by about 1 Stop and not the highlights – this is something like what the camera does when making the JPEG file in-camera.


    The value of HTP in regard to shooting JPEG:

    If one IS shooting a scene of wide Dynamic Range - there is the potential of the raw data to be recorded in suitable appropriate dynamic range but the highlights being blown when a “standard” JPEG conversion curve is applied to the raw data to generate the JPEG (in-camera).

    So, (as per the Canon User Manual), HTP has a useful application for those who use JPEG capture.

    I think this is where the concept that ONLY the JPEG data is affected comes about.

    But, the fact (my hypothesis) still is - that when using HTP the raw file is indeed, affected.

    *

    The value of HTP in regard to shooting raw ONLY:

    One might choose to use HTP for raw capture: if the idea of (generally) underexposing at capture time and then boosting the shadows and mid-tones in post-processing is a good approach. I cannot see that there any end-game advantage in this practice, however.

    *

    The value of HTP in regard to shooting raw + JPEG:

    I shoot raw + JPEG(L). I do see an advantage of using HTP, sometimes: this is when I expect that my JPEG file will be used (quickly) SOOC, or with minimal Post Production.

    *

    Although it appears that HTP has a scatty RANGE of responses (outcomes), depending upon the type of lighting on the scene; I have found HTP quite predictable if one often shoots in similar lighting scenarios: which I do.

    I think that if you (Steve F) really want to understand HTP and assess any potential value of the function to your Photography, then you need to give it a lot more a go than merely “a brief play at lunchtime” and also I suggest that you need to consider how the HTP function might be applied to which of the (maybe repetitive) specific shooting scenarios in which you find yourself. To that end, I suggest that you first question the reasons for your shooting (only) JPEG.

    *

    There are many discussions about HTP in various forums.

    All the conversations which I have read where Photographers have used HTP and have also made specific A/B comparisons of both their raw and JPEG files (and Post Production Programmes): their results concur, along similar lines, to mine which I have outlined above.

    I have not seen any definitive paper from Canon, which outlines the detailed functionality of HTP.

    *

    P Mode:

    It may have been a tongue on cheek comment, but I shall nonetheless respond:

    "P Mode" is the most misunderstood (and also maligned) of all the Automatic Camera Modes.

    P Mode can be an exceptionally useful Camera Mode and it would bode well for a complete understanding of the functionality of P Mode, especially if one is charging money to shoot Weddings, using a Canon EOS DLSR: and especially if one is shooting JPEG only.

    Perhaps the functionalities and usefulness of "P Mode" ARE indeed understood by you and that was why the comment was made, linking P Mode and Weddings and HTP.

    This would indeed make sense to me.

    WW
    Last edited by William W; 21st May 2013 at 12:01 AM.

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    Re: I'm still not convinced...

    High Light Tone Priority is achieved by uinderexposing and in doing so reducing the risk of over exposing and saturating the sensor. Then the image is amplified to bring back correct tonal values. Hence the lowest ISO cannot be set with it. Also there will be more noise in the darker colours where extra amplification has taken place. However it reduces the risk of blowout in the highlights wich can destroy an image.

    In bright high contrast condisitions I tend to underexpose 1/3 or 2/3 to keep highlights and then compensate with exposure on developing the raw file.

  9. #9
    RustBeltRaw's Avatar
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    Re: I'm still not convinced...

    Interesting, and very thorough, Bill. If I get a moment this evening, I'll run a few informal tests with my 60D and see if any ISO or other differences show up in the RAW and JPEG EXIF data.

  10. #10

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    Re: I'm still not convinced...

    Thankyou for your response Bill - I'll have a thorough read later when I return home tonight.

    And yours Loosecanon.
    Last edited by SteveF; 21st May 2013 at 04:05 PM. Reason: noted Loosecanon.

  11. #11

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    Re: I'm still not convinced...

    Quote Originally Posted by William W View Post
    The following comment is in respect of Canon DLSR Cameras and based upon my observations and it is a synopsis of my hypothesis of HTP functionality.

    *

    I conclude that HTP does affect the raw file.

    It occurs to me that if HTP enabled the camera underexposes by (about) 1 stop. This logically seems to be done by lowering the ISO.

    This lowing of the ISO, might be akin to how the camera actions the selection of the “intermediate” ISO, such as: ISO 500 & ISO 640; ISO 125 & ISO320 etc.

    This data IS recorded to the RAW file.

    *

    In-Camera JPEG conversion:

    When the camera generates the JPEG file it occurs to me that the HTP flag is noted and a curve is applied to boost the shadows and mid-tones without affecting the highlights. HTP is useful for shooting JPEGS, to achieve this effect, SOOC.

    *

    Post Production Programmes:

    It occurs to me that when (most) Adobe Products see the HTP flag they automatically boost the exposure slider by one stop.

    It occurs to me that Canon DPP manages HTP, slightly differently. When DPP sees the HTP flag set on the underexposed RAW file, it applies a different curve in the RAW conversion which again will selectively boost the shadows and mid-tones by about 1 Stop and not the highlights – this is something like what the camera does when making the JPEG file in-camera.


    The value of HTP in regard to shooting JPEG:

    If one IS shooting a scene of wide Dynamic Range - there is the potential of the raw data to be recorded in suitable appropriate dynamic range but the highlights being blown when a “standard” JPEG conversion curve is applied to the raw data to generate the JPEG (in-camera).

    So, (as per the Canon User Manual), HTP has a useful application for those who use JPEG capture.

    I think this is where the concept that ONLY the JPEG data is affected comes about.

    But, the fact (my hypothesis) still is - that when using HTP the raw file is indeed, affected.

    *

    The value of HTP in regard to shooting raw ONLY:

    One might choose to use HTP for raw capture: if the idea of (generally) underexposing at capture time and then boosting the shadows and mid-tones in post-processing is a good approach. I cannot see that there any end-game advantage in this practice, however.

    *

    The value of HTP in regard to shooting raw + JPEG:

    I shoot raw + JPEG(L). I do see an advantage of using HTP, sometimes: this is when I expect that my JPEG file will be used (quickly) SOOC, or with minimal Post Production.

    *

    Although it appears that HTP has a scatty RANGE of responses (outcomes), depending upon the type of lighting on the scene; I have found HTP quite predictable if one often shoots in similar lighting scenarios: which I do.

    I think that if you (Steve F) really want to understand HTP and assess any potential value of the function to your Photography, then you need to give it a lot more a go than merely “a brief play at lunchtime” and also I suggest that you need to consider how the HTP function might be applied to which of the (maybe repetitive) specific shooting scenarios in which you find yourself. To that end, I suggest that you first question the reasons for your shooting (only) JPEG.

    *

    There are many discussions about HTP in various forums.

    All the conversations which I have read where Photographers have used HTP and have also made specific A/B comparisons of both their raw and JPEG files (and Post Production Programmes): their results concur, along similar lines, to mine which I have outlined above.

    I have not seen any definitive paper from Canon, which outlines the detailed functionality of HTP.

    *

    P Mode:

    It may have been a tongue on cheek comment, but I shall nonetheless respond:

    "P Mode" is the most misunderstood (and also maligned) of all the Automatic Camera Modes.

    P Mode can be an exceptionally useful Camera Mode and it would bode well for a complete understanding of the functionality of P Mode, especially if one is charging money to shoot Weddings, using a Canon EOS DLSR: and especially if one is shooting JPEG only.

    Perhaps the functionalities and usefulness of "P Mode" ARE indeed understood by you and that was why the comment was made, linking P Mode and Weddings and HTP.

    This would indeed make sense to me.

    WW
    Let me clear up a few things as to how I approach things. I do shoot weddings,dance, studio and sport. Very few weddings and mainly in the bottom bracket for those that have a limited budget. A lot of dance, very little studio and a huge amount of sport (cyclesport only).

    My methods are complete control of exposure and white balance. I'm a bit of a pain in the butt getting white balance right but when 1500 images pop up in my viewer needing no correction after a long day it makes me feel good. So, in truth I haven't used 'P' for Program but am aware of program shift and find many of the attributes of program would be handy. I do shoot AV almost exclusively. My comment was part tongue-in-cheek about shooting my next wedding in P.

    The kit I've got is all high end 1-series and quite honestly 'straight' jpeg capture is perfectly fine for the market I'm aiming for hence looking at HTP to further enhance my 'in camera' production. It's just that there are some things like HTP and ALO I shy away from thinking it's robbing me of the control and predictability I like.

    It's very difficult I'm finding to get info on jpeg shooting just to get sooc images. Manufacturers web sites give little info as we've found. Some praise HTP and such and then the raw boys come along and frighten the poor little blighters off

    I have posted this elsewhere and all I got was 'just shoot raw'. I don't want to, thankyou. I'm just wanting some info on how this works!

    Thanks for your input folks.

  12. #12
    William W's Avatar
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    Re: I'm still not convinced...

    Quote Originally Posted by SteveF View Post
    Let me clear up a few things as to how I approach things. . . etc
    Thanks for the considered and detailed response.
    It is understood and very useful to write these few additional remarks which hopefully will assist:

    Quote Originally Posted by SteveF View Post
    [I do shoot a] lot of dance, very little studio and a huge amount of sport (cyclesport only).
    And
    Quote Originally Posted by SteveF View Post
    there are some things like HTP and ALO I shy away from thinking it's robbing me of the control and predictability I like.
    Reiterating: It’s not the repetitiveness of the shoot type: it is the repetitiveness of the similar lighting scenario which will afford you reasonably consistent results and allow you to choose whether HTP will be useful.

    For example (taking cycling and thinking up a possible situation) this lighting scenario which often might occur as you make a typical camera viewpoint:

    “bikes will bank around street corner"

    SHOOT: 45° angle to cyclist - capture full frame single cyclist // ALSO // be prepared to capture multiple cyclists // Crash possible . . . etc.

    LIGHTING: street corner in shade and buildings in part of background hard full side sunlight.

    OPTIONS: consider using HTP for wider shots of more than one cycle or of peloton when large amount of image real-estate is taken up with background buildings. Consider rigging one camera with wider lens and setting HTP enabled on it.

    *

    Quote Originally Posted by SteveF View Post
    I haven't used 'P' for Program but am aware of program shift and find many of the attributes of program would be handy.
    My comment was indeed I respect of understanding the functionality and usefulness of Program Shift.

    Moreover, the other key application for Weddings: the understanding of the multiplicity of functionalities of P Mode in respect to using Flash as Fill.

    *

    Quote Originally Posted by SteveF View Post
    'straight' jpeg capture is perfectly fine for the market I'm aiming for hence looking at HTP to further enhance my 'in camera' production.
    Understood.

    I was merely asking: “have you thought though why you are using 'JPEG only'? – if not - then do so, critically”

    *

    Quote Originally Posted by SteveF View Post
    It's very difficult I'm finding to get info on jpeg shooting just to get sooc images.
    Yes.

    I cut my studio over to Digital from Film around 2004. One of the tasks I set myself was workout how we could have JPEGs SOOC emulate the various films which we used. The research and learning I did was not used for what I intended, but it has served me in other ways (often the case).

    In summary what I ended up with was:

    • A grid with film types / scene (e.g. “Portrait Fuji”; Portrait Kodak”) outcomes on one axis: and lighting scenarios on the other (e.g. “Daylight No Fill”; “Daylight Flash Fill”; “Inside Daylight Flash Fill”) – and in each box where these intersect, were the “In-Camera JPEG Styles”.

    • I edited down to four film/scenes and five lighting scenarios – for the tasks you listed, would have fewer I expect and you would include HTP in the outcome boxes.

    • Also what I found was JPEGs SOOC required sharpening and it is (generally) better to do that in PP, than in camera.

    • I also found that camera model (definitely) and ISO use within one camera (sometimes) were independent of my results – what I mean is: I needed a GRID for EACH camera and sometimes, when using one camera, changing the ISO would necessitate tweaking the “In-Camera JPEG Styles” – this latter point about ISO / JPEG Styles seems to be more obvious with the early model cameras I used, (20D, 30D and 50D), and not so much with the later APS-C xxD; xD and the 5D models.

    • Although I use pool 1 Series cameras - I have not had the need to made this type of grid, for any EOS 1 Series DSLRs

    *

    Quote Originally Posted by SteveF View Post
    then the raw boys come along and frighten the poor little blighters off
    haha.

    Their argument doesn’t hold water – IF there is a rationale for shooting JPEG. I rarely argue that, though.

    WW
    Last edited by William W; 21st May 2013 at 10:28 PM. Reason: because I make spelling mistakes when I type fast

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