Tutorial: Reading your Histogram

[JakeB.]

The histogram is an invaluable tool in correctly exposing your images and being able to extract the maximum amount of color information from them. A histogram represents the roughly 5 stop dynamic range of most sensors. This translates into a 12 bit image (what RAW captures), which is able to capture 4096 tonal values. The brightest colors of your image are represented on the right side of the histogram... the darkest colors on your left. The 4096 are not evenly distributed across the brightness of your image. As this shows, the brighter your image is, the more color information you capture. Ideally, for those that are interested inextracting the most out of your images in post, you would get the most info on the right as possible, without actually touching the end. When your histogram is touching the end, that's when you've reached the limit of color information... this is referred to as blowing the highlights. For those not interested in post processing your images, you would ideally spread your histogram across the three middle stops. Here are a few shots and their associated histograms. Properly exposed: Properly exposed histogram: Exposed Right: Generally ideal for extracting more color info... Exposed Right histogram: But, here the reds are clipping pretty bad, which means a loss of info... you can actually see the effect above. Most cameras have a display screen that shows any blown highlights... here's an example: Bigger versions of the highlights screen are here and here Over-exposed: Over-exposed histogram: Over-exposed histogram/highlights: Bigger versions here and here Exposed Left: Exposed Left histogram: Under-exposed: Under-exposed histogram: As I mentioned before, whenever the histogram touches the left end it means that you have exceeded the limit for capturing color information... the areas that it's pertaining to are pure white. In the same, whenever the histogram is touching the left end it means the you have exceeded the limit there as well... those areas are completely black, with no other color info. This is quite a confusing topic, so feel free to ask questions... or if anyone else has input, feel free to post it. Luminous Landscape has nice write-up's on understanding exposure and exposing to the right if you want to read more. Also, some of these shots are blurry... if you mention it I'll punch you in the nads

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[MSchu]

Let me ask you this... why would you want to do this in the camera as opposed to in CS?

PS(Post script)... to touch me you have to move to me, this allows me the oppertunity to intercept your movement.(Jeet)

Peace
Schu

[Egg-weezy]

Thanks for the tutorial, never really understood the histo feat.

[JakeB.]

Originally Posted by MSchu

Let me ask you this... why would you want to do this in the camera as opposed to in CS?

The idea here is to capture as much information as possible in camera, so that the most can be made of the image in post production.

If the image you capture has a bunch of pure black or pure white information, even if shot in raw, you can never recover it all.

[Import Driver]

Awesome write up Jake! You brought out very good points.

I want to point out to people that in Jakes example picture there are a lot of whites (or close to white) and not a lot of true blacks. If it were a picture with a lot of true blacks (like a lot of black markers) then the information (or large hump) would be mostly to the left where as the smaller hump would be on the right since there would be very little true whites. So your histogram wont look exactly like Jake's, it will depend on what you are taking a picture of. The most important part - as Jake stressed - is that you aren't touching the ends.


Wow, Jake does a much better job wording things then me.

[Ronin150]

Nah import you just backed up what he said.

Jake thanks for explaining that. I sorta understood what was going on before, but this just helped out more. Thanks.

[DC4GB]

Wow this was exactly the type of explanation I was looking for. Thanks!

[o.G.A.g.]

great writeup. this should be very usefull for the beginner and maybe amatures who dont use this tool.

[coneheadsracing]

Originally Posted by Import Driver

Awesome write up Jake! You brought out very good points.

I want to point out to people that in Jakes example picture there are a lot of whites (or close to white) and not a lot of true blacks. If it were a picture with a lot of true blacks (like a lot of black markers) then the information (or large hump) would be mostly to the left where as the smaller hump would be on the right since there would be very little true whites. So your histogram wont look exactly like Jake's, it will depend on what you are taking a picture of. The most important part - as Jake stressed - is that you aren't touching the ends.


Wow, Jake does a much better job wording things then me.

Was just about to ask this question, thought maybe some cameras were different me using on olympus and all. Thanks for the write up guys, i just recenlty turned on my highlights option, i like using that too.

[MSchu]

intesting... while I have been practicing photography for over 25 years, I just recently digital... I have traditionally always controlled histograms in PS. sounds like potentially I may have been loosing 5 or 10 of tonal detail, I will have to look into that.

Peace
Schu
(Evolt FTW)

[JakeB.]

Glad I could shed some light

Originally Posted by Import Driver

I want to point out to people that in Jakes example picture there are a lot of whites (or close to white) and not a lot of true blacks. If it were a picture with a lot of true blacks (like a lot of black markers) then the information (or large hump) would be mostly to the left where as the smaller hump would be on the right since there would be very little true whites. So your histogram wont look exactly like Jake's, it will depend on what you are taking a picture of. The most important part - as Jake stressed - is that you aren't touching the ends.

Thanks for adding that Jesse... an important point.

[DC4GB]

Jake, I'm shooting with a D50 and possibly read that I dont' have a RGB histogram, but instead a BW histogram? If so is reading the BW histogram any different than of a RGB?

Also thanks for opening up a thread on such an important aspect of shooting digital.

[JakeB.]

When you look at the examples of my histogram, you see the three RGB color histograms and the b&w histogram.

To answer your question: Yes, you would read it the same way.

[vc]

Thanks for this write up, I understand a histogram better than before.

[just Touge]

Jake is smart.

Also remember that blck is the presence of all color in digital language and white the absence, therefore if you are going to be able to recover from one or the other, underexpose rather then over.

[Swags04]

Also a quick gauge when shooting on the go... Always make sure the white is the whole way across the bottom, If it comes up short, your photo will be wrongly exposed.