Lightroom 3.x and Highlight Tone Priority

Just wondering if Lightroom actually does anything with highlight tone priority?

I'm pretty sure LR ignores the info for that; you'd have to import through DPP. It's heresay, as I don't have any documentation that says that explicitly, though.

Lightroom does recognize Highlight Tone Priority. But at this point we have to pause. I've read reports that HTP does not record into the Raw data but just puts a "flag" in the camera exif that Lightroom reads and applies.

Now, this sounds kind of weird to me, but the technology could line up.

Highlight Tone Priority works like this: you turn it on then you set an ISO (the numbers show up weird). But, you can't set the ISO to 100, but only to "2oo". You "lose" a stop of ISO.

What the camera does then is this: you take the shot, and the camera actually reads the signal from the lower ISO, in this case 100, meaning that the signal is unexposed in comparison to your desired settings, and then processes this signal by applying a curve to boost the shadows and midtones while holding back the highlights. It's nifty if shooting jpegs but not so good if you are shooting Raw and want more control without just giving up on, say, shadow noise.

But, HTP does "show up" in Lightroom. Like I said, there is research that indicates that it is a flag that LR reads and applies -- evidently apps that read the actual Raw data and present it demonstrate this. But still LR applies it, so if you are a Raw shooter and want full control of your images, well, avoid thing like this!

Good stuff, thanks Tony!

When HTP was first introduced and for more than a year afterward LR/ACR did not recognize HTP. All you got was an underexposed image, one stop under. This I can testify to from tests I did two years ago. Subsequently I heard that Adobe had begun to read the flag and apply a curve. However some people said it was a flat curve, i.e., merely a kicking of the exposure up by a stop. I think I will do a test or two again, although I never use HTP, but just out of curiosity. I'll be back.

Here's a "thing" I did testing it in March of '08 which to me showed that LR did apply it (LR1.x) but I don't have the technical details:

http://www.pbase.com/t​onylong/mk3_htp_test

I'm a bit confused right now because I just shot two RAWs, one with htp and one without, and in both DPP and LR they are identical. I expected that at least in DPP there would be a difference in the lighter part.

I also discovered that my 5D2 shoots about half a stop underexposed in Av/0 EC, which I didn't know because I have always shot M and ETTR with it. I didn't bother to reshoot with +EC, so the following illustration will look dark. It is also flat because it is in Neutral P.S. with Contrast at 0.

I will try the same with my 40D when I get a chance tomorrow.

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Elie, I'm always a bit confused!

So, you are saying that with the Raw neither DPP or LR appear to be applying the HTP? Hmm. I wonder if something has changed, because with my tests with the 1D3 LR seemed to be...but this was over two years ago.

Might be a glitch in my 5d2. I'll have to investigate further. The Exif says htp "enabled", but I don't know if that is what DPP reads or if there is another flag.

Elie, when I tested it out with the 1D3 I shot Raw+jpeg, so I could directly compare. If you checked that link out you saw that the HTP was showing up in LR, fairly close to the jpeg.

tzalman wrote in post #10962801
I'm a bit confused right now because I just shot two RAWs, one with htp and one without, and in both DPP and LR they are identical.

Well, I see an ever so slight difference in the (left of the) histogram...

Also, I'm a bit confused: What settings?
Spot metered on the gray patch, same ISO, shutterspeed and aperture, only HTP on vs. off?

(Never bothered with HTP, can you tell? )

HTP does 1 stop "-" in exposure . This will imply that HTP may help photographer in the areas like snow,bright light conditions but darkens when shot in low light.