Understanding Canon DPP histogram

[Davejl]

I would appreciate some guidance with using the Canon DPP histogram. I understand how the levels histogram in PSE (mine is v. 7!) works, but DPP confuses me. (My raw converter of preference for my 450D was Capture One, but since upgrading to the 70D, I rely on DPP. I just don't like the colour I get from using PSE with CR2 to DNG conversions).

If I move the lightness slider in PSE to the left to meet the right side of the histogram, the image is brightened. But if I do the same in DPP, and make the right-sided vertical meet the histogram, the image brightens to the point of total over-exposure. I'd be grateful for an explanation.

Also, how does one recover blown highlights. It seems that pulling down the top "bar" gets rid of the highlight warning, but is this maybe just analogous to moving the output slider in PSE, i.e. not really recovering blown detail, but simply replacing white with grey?

I find that the dedicated "highlight" slider does little.

Incidentally, if I use the guidance of the histogram in the Silkypix software for my Fuji X100 shots, I tend to find that the resulting TIFF can be brightened further in PSE according to the PSE histogram than the Silkypix histogram indicated.

[Polar01]

Dave I myself use ACR and Photoshop CC to process my images in, however I can answer one thing for you, if you have blown out the highlights there is no way that you can get any detail back. Pure White is pure white no detail in that at all.

Cheers: Allan

[Davejl]

Hi Allan,

I appreciate that pure white (e.g. sun glinting on metal) can't be changed, but what I really mean is that I'm looking for the DPP equivalent of the PS recovery slider.

Incidentally, I think I've posted this thread in the wrong area but can't work out how to move it at present.

Dave

[Polar01]

Dave go to "Quick Links" on the banner above, then "View Site Leader", then chose either Donald or Grumpydiver as both are active and ask them to move the thread. Just click on "PM" private message and send them the message.

Cheers: Allan

[rpcrowe]

Although many photographers use DNG as a portion of their image editing workflow, I have not liked the results when I converted CR2 to DNG (using CS6 and Adobe Bridge). I work with PSD files. There is an amount of concern regarding the long-term viability of imagery in PSD format but, I don't worry about that aspect. I am 75 and PSD will certainly outlive me

[Rebellion]

Hi Dave ,mabe this link will help you...

http://www.learn.usa.canon.com/resou...stograms.shtml

[Dave Humphries]

Incidentally, I think I've posted this thread in the wrong area but can't work out how to move it at present.

Thread now moved, thanks for PM.

Easy-peasy - just don't do it again

Cheers, Dave

PS: I'll welcome you in the usual thread later

[george013]

If I move the lightness slider in PSE to the left to meet the right side of the histogram, the image is brightened. But if I do the same in DPP, and make the right-sided verical meet the histogram, the image brightens to the point of total over-exposure. I'd be grateful for an explanation.

How do you see that? If it are those blinking fields in the image you might have a look at the treshold.

George

[dje]

I would appreciate some guidance with using the Canon DPP histogram. I understand how the levels histogram in PSE (mine is v. 7!) works, but DPP confuses me. (My raw converter of preference for my 450D was Capture One, but since upgrading to the 70D, I rely on DPP. I just don't like the colour I get from using PSE with CR2 to DNG conversions).

If I move the lightness slider in PSE to the left to meet the right side of the histogram, the image is brightened. But if I do the same in DPP, and make the right-sided vertical meet the histogram, the image brightens to the point of total over-exposure. I'd be grateful for an explanation.

Also, how does one recover blown highlights. It seems that pulling down the top "bar" gets rid of the highlight warning, but is this maybe just analogous to moving the output slider in PSE, i.e. not really recovering blown detail, but simply replacing white with grey?

I find that the dedicated "highlight" slider does little.



Incidentally, if I use the guidance of the histogram in the Silkypix software for my Fuji X100 shots, I tend to find that the resulting TIFF can be brightened further in PSE according to the PSE histogram than the Silkypix histogram indicated.

Hi Dave

I don't have the latest version of DPP but have v3.12.3. Here are a couple of screenshots showing the RAW Curves adjustment tool (which includes a view of the histogram). Is this what you are referring to ? Click on the images to get a full size view.

The first image , which is significantly underexposed, shows the un-adjusted view. The second image shows the effect of sliding the right hand vertical slider to the left by two stops. (If you look closely you will see the little triangle has moved to the left, from +4 to +2). This causes a significant increase in "brightness". This occurs because the tonal range is stretched out over a wider set of values. This is a similar adjustment to the right hand slider of the Levels adjustment in PS however there is one big difference - the DPP curve is shown with a logarithmic horizontal scale or in other words is shown in exposure stops, whereas in PS it is linear. The adjustment I made was to shift this by 2 stops (which would be equivalent to shifting the white point in PS Levels from 255 down to 64 !





I'm afraid DPP is not known for it's ability to recover highlights in raw (like ACR or Lightroom can).

Dave

PS. When using a Levels type adjustment, there is no need to move the right hand slider all the way to the top edge of the histogram - just move it until the brightness looks right.

[pnodrog]

Also, how does one recover blown highlights.

If you have "blown" the highlights there is no editor/etc that can recover them as there is no information available and grey is the only logical result of darkening the highlight. However if there is still a little variation between the RGB channels some recovery may well be possible depending on the software in use. A trick to fake recovery in some situations e.g. blown highlights in water fall or gloss on nose or cheek etc, is to clone from an appropriate source using the darken mode and transparency set very low. This can rescue an image in an emergency.

The real answer is to never over expose to the extent you get blown highlights but I am sure you know that.....

[Davejl]

Hi Dave,

Many thanks. I think you've cleared the mystery up for me. I think I have the same version of DPP as you, actually (I haven't got the new 64 bit version and won't be getting it until my computer needs replacing). I should have posted screen views as you have, but I'm not up to speed on CIC website yet.

So the essential difference is the logarithmic nature of the DPP graph. I had found that moving the right hand slider left a little bit (usually a very little bit) seemed to do the trick. Does doing this achieve anything that simply moving the brightness slider does not? I also wonder why Canon chose this type of histogram. By the way, maybe you could throw light for me on the "linear" tick box, too. If I click on that, the image darkens drastically.

I'm also unsure of the purpose of the RGB histogram. The DPP manual seems to imply that it is best to leave it alone?

Thanks,

Dave

[Davejl]

Hi Paul,

Thanks. Yes, I was meaning the recovery that is possible when (as I understand it) one of the three colour channels isn't actually totally blown out. DPP seems poor here. ACR is much better, but I don't seem to get pleasing colour with this (things seem to get either a magenta or yellow bias). Capture One is good, but I haven't upgraded to the version that can handle my 70D files.

For my Fuji X100 raws, the supplied Silkypix software (detested by many, it seems) is actually my favourite raw converter. Unfortunately, it doesn't handle DNG, so I can't play with my Canon files there.

Cheers,

Dave

[dje]

Hi Dave,

Many thanks. I think you've cleared the mystery up for me. I think I have the same version of DPP as you, actually (I haven't got the new 64 bit version and won't be getting it until my computer needs replacing). I should have posted screen views as you have, but I'm not up to speed on CIC website yet.

So the essential difference is the logarithmic nature of the DPP graph. I had found that moving the right hand slider left a little bit (usually a very little bit) seemed to do the trick. Does doing this achieve anything that simply moving the brightness slider does not? I also wonder why Canon chose this type of histogram. By the way, maybe you could throw light for me on the "linear" tick box, too. If I click on that, the image darkens drastically.

I'm also unsure of the purpose of the RGB histogram. The DPP manual seems to imply that it is best to leave it alone?

Thanks,

Dave

Dave I rarely use DPP so I don't have an in-depth knowledge of it.

The actual mechanism of Brightness adjustments can vary from one piece of software to another so it's hard to know exactly what DPP does. I would say however that it produces slightly different results to the tonal range adjustment associated with the histogram.

The log scale is possibly used because Canon describe this adjustment as a Dynamic Range adjustment and log scales are usually used with Dynamic Range values.

The Linear tick box appears to remove the tone curve and gamma encoding making the file truly linear. This makes the image very dark as it is being viewed with an opposite gamma curve applied to the monitor. There can't be any colour management going on when viewing this. Canon say this option is for use when other specialised software is to be used following raw conversion. Personally I can't see any use for it.

I've always found DPP to be quite basic with a user interface that is not particularly intuitive. The tonal adjustment associated with the histogram in the RGB tab may be intended to be used if your are using DPP to edit a jpeg rather than a raw file. There would seem little point in using both of these adjustments on a raw file.

Dave

[Davejl]

Dave, thanks for the explanation. If I got better colour results from ACR I would use it more, since I find it more intuitive. DPP seems to be a curious combination of the basic and the overly-complicated. Having said that, I've got some results that I'm very happy with. And what I am especially pleased with is how I've managed to improve shots taken five years ago with my Canon 17-85 lens, where the DLO facility, which didn't exist then, has worked wonders on some pretty bad CA and improved peripheral sharpness.

Dave

[davidedric]

If you want a view of how adjustments are changing the tone curve, an image of a step wedge running from white to black is useful.

The histogram is than a series of vertical lines, and by moving the controls you can see how they shift around. It's not perfect. In Lightroom, for example, the controls are to some extent image adaptive, but it gives a helpful guide.

Dave