The Power of RAW

[Juan Aragonés]

This is a post that I wrote some weeks ago in my blog about processing files in Photoshop and the advantages of overexposure in digital. While I was writing, I was listening at the radio an old song from the 80´s. "The Power of Love" by "Frankie Goes to Hollywood" and I decided to use the title of that song for this entry in my blog. In my last post here, I talked about overexposure in digital and how I use it for a better performance of my processing job. Usually, I try to overexpose my images between +0,3 and +1EV, sometimes even more, because I can do a better job in processing the middle tones and the dark areas in images with a high dynamic range while avoiding the effects of digital noise. But sometimes I go a bit far overexposing and I end with a very bright image, a good candidate for the trash… at first glance. This image of a squacco heron is a good example of what I am talking about (I think it was posted here in the avian forum some time ago). The RAW is clearly overexposed (all those flagging red areas in the bird), more than one and a half stop. In this case, I failed the exposure because I was waiting for another bird in a place with different light conditions). Yes, I was trying to overexpose but not so much!

Fortunately I was shooting RAW and there was no problem to fix the image during the RAW conversion. I moved the exposure slider to -1,65 and the RAW conversion made its magic. Plenty of details in the white areas of the bird. No hot areas or white´s clipping and no problem of noise instead of the fact that I was using ISO 640 (remember that, instead of the fact that there was plenty of light, I was trying to overexpose and that is the reason for such a high ISO). It is amazing the things that you can do with a RAW and this is just but a very simple example. Next time that you have an image like this in your camera´s screen think twice before send it to the trash ;-)
Nikon D300, AFS Nikkor 500VR, f7, 1/1600s, ISO640, Manual exposure

[Juan Aragonés]

And here is the fixed version :)

[Lorant Voros]

Thanks Juan for posting this. It would be a very useful thread for the ER. I still have friends who shoot JPEG instead of RAW. I will send them your blog:-).

[Stu Bowie]

Juan, I agree 100% that over exposing is the way to go. Good recovery on the whites here, and you have reinforced the fact that not all images must go to the bin.

[Tom Graham]

Hmm, I think I need a dictionary to help with photo terms. Specifically, terms underexposure and overexposure. To me they both mean the total amount of light (lux seconds) that falls -outside- of the measurement capabilities of sensor it falls on. So overexposure means that the total light, lux secs, was not measured by the sensor. Thus information about it was lost. If that information is lost, RAW or PS can not recover it. If "overexposure" does not mean this, then what is the term that does? Because I now need to add to my personal dictionary.

Time to so some reading by Ansel Adams?

Tom

[arash_hazeghi]

Nice demo Juan, it works out as long as you don't clip any of the channels (i.e. saturate the pixels) ;) This is a good method for noisy cameras like D300, 50D etc. For low noise cameras like 5D, 1D MKIV, D3 etc. noise is not an issue so I try to stay on the safe side not taking chances to overexpose :)

[Ray Rozema]

I have two questions.
Juan, do you convert using NX2 or PS? I ask because I have read that converting Nikon images is best done w NX2.
Arash If something is overexposed is also clipped? Apparently not

Thanks very much for the help.
Ray

[Desmond Chan]

Sometimes whether you can recover the "lost" highlight details depends on what camera you use. This means that even if the clipping signals are there, the details can still be covered. Fujifilm S5 Pro can do that. I have shot indoor shot with S5 in which everything outside the house looks totally blown, but still could be recovered. Not only that, I could even make the outside looks under-exposed. I read that Nikon D3x is nearly as good in that department.

Having said that, all cameras have their limits and none can do magic once that point is passed.

[arash_hazeghi]

I have two questions.
Juan, do you convert using NX2 or PS? I ask because I have read that converting Nikon images is best done w NX2.
Arash If something is overexposed is also clipped? Apparently not

Thanks very much for the help.
Ray

Nope, The histogram and blinkies in the camera are coming from the 8 Bit JPEG file, so what is shown as overexposed (look at Juan's first crop) may still have data in the 14Bit or 12Bit RAW file, but once the RAW levels are saturated there is nothing you can do (i.e. clipped channel in RAW) NX2/Canon DPP can show you full RAW histogram, photoshop can only show 8 Bit histogram. It is hard to determine at what exposure the RAW levels will become saturated, so it is risky. usually up to 2/3EVis fine but sometimes if the bird is completely white like egrets this can toast the whites in RAW.

Desmond Fuji S5 is a special camera it has two photo diodes per pixel, once the primary diode is saturated it uses the secondary diode to read the highlight values therefore comparison is irrelevant. All other cameras have single diode per pixel location.

[Tom Graham]

Aaah, so the new word is "saturated". "oversaturated" has replaced "overexposed"?
Tom

[Desmond Chan]

Desmond Fuji S5 is a special camera it has two photo diodes per pixel, once the primary diode is saturated it uses the secondary diode to read the highlight values therefore comparison is irrelevant. All other cameras have single diode per pixel location.

Arash, I knew about the S5 and I have one myself. I am not comparing cameras and hence I started my previous post with "depends on what camera you use." I was simply pointing out that some camera does happen to be able to handle over-exposure better, and it's true. :) How that camera achieves that is secondary as far as the truthfulness of that statement is concerned, in my opinion.

[Michael Gerald-Yamasaki]

Juan,

Greetings. Sure, raw converters have the capability of recovering some highlights, but in your example the seemingly blown whites are there at least in part by the +50 brightness (probably some contribution of the +25 contrast, too). What is pushed to the right by brightness is being pushed back to the left by lowering the exposure setting in raw conversion.

If you have a blown wing like the first shot, with neutral settings (brightness, contrast at 0) it's been my experience that it is pretty much unrecoverable. Certainly not something to shoot for. ymmv.

Cheers,

-Yamo-

[Tom Graham]

I see no advantage to overexposing in digital. The brightest, highlight, information will be lost. By definition of what "overexposure" is. While if you underexpose slightly, the highlight information will still be there.
When you say you overexpose your images between +.3 and +1EV, what metering are you using, matrix, composite, spot, or?

Tom

[Juan Aragonés]

Hi Ray, I didn´t receive an email feedback from BPN about your question about ARC and Nikon capture so I apologize for not responding sooner. In the past, I used Nikon capture for my RAW conversions and I really liked some of the interesting features of the software like the “U-point” technology but I was really frustrated by the slow working of the program and missed a lot a good interface with Photoshop so I decided not to use more and I began to work with Adobe Raw Converter. ARC is really fast and performs very well, it has a nice interface for Photoshop and I am really happy with it, especially with the version integrated in CS4 that allows me a lot of control on the RAW conversion. I have tested Capture NX2 too and it seems to me that works better than previous versions but I have seen not a great difference between NX2 and ARC in terms of color management (I know that a naked eye is not the best way to test these kind of things but my prints looks really satisfactory to me). Perhaps NX2 has some proprietary features that helps with a better performance during the color conversion process, I really do not know, but for me it really doesn´t matter because I relay on my eye and calibrated monitor for color management (you know, just works for me).
Of course, what works for me may not work for a different person due to different workflows. In my workflow, most part of the key steps are performed in Photoshop, while the RAW conversion is just about 40% of the total process.
Hope this helps,
Juan

I have two questions.
Juan, do you convert using NX2 or PS? I ask because I have read that converting Nikon images is best done w NX2.
Arash If something is overexposed is also clipped? Apparently not

Thanks very much for the help.
Ray

[Juan Aragonés]

Good point Michael. I am going to have a look on the RAW file to see if the red blinking areas are explained by the +50 brightness and +25 contrast and will put the sliders of brightness and contrast at 0 to see if the red blinking areas are gone. By the way, I have my camera with neutral settings and the increase in brightness and contrast was made, automatically, by the RAW converter.

Sorry for the delay in responding to you :)

Juan,

Greetings. Sure, raw converters have the capability of recovering some highlights, but in your example the seemingly blown whites are there at least in part by the +50 brightness (probably some contribution of the +25 contrast, too). What is pushed to the right by brightness is being pushed back to the left by lowering the exposure setting in raw conversion.

If you have a blown wing like the first shot, with neutral settings (brightness, contrast at 0) it's been my experience that it is pretty much unrecoverable. Certainly not something to shoot for. ymmv.

Cheers,

-Yamo-