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Do you ever use the histogram?


Sanford

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Show & tell = credibility. Strong opinion and aggressive expression require "The proof of the pudding is in the eating" in this case, the viewing - posts or portfolio.

 

Referring to authorities on the subject of histograms and whoever else has written about this subject does not equal credibility, but show & tell does? Feeling that one cannot do a better job than for instance Adobe or Real World books equals a lack of credibility? Bruce Fraser, rest his soul, would not agree.

 

Lighten up, Sandy.

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i wish someone would explain how looking at graphs rather than the picture makes any sense?

 

I spend more time looking at pictures than graphs, but graphs can sometimes tell you if some parts of your picture are getting clipped (going over or under the displayable brightness range) during processing. If thats a very small area in the image, it may get unnoticed while viewing on small monitors, but may be revealing in large displays or prints. Thats just one benefit I find in checking numbers. The other benefit is, if the brightness of the image pixels are concentrated over a smaller range and not well distributed across the 8-16 levels that the jpeg or tiff provides, histogram can tell you that, while eyes sometimes get deceived. Redistributing the brightness over the larger range improves contrast and visibility of darker areas, and in general improves the quality of the image. Usually I use the histogram as a supplementary guide in my visual inspection of an image, but not as a substitute for looking at the image.

 

I will find some examples later on.

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Examples of how to use histograms and what they can do for you are all over the place in photo editing software manuals, photo editing books, photo forums and the internet in general. Do I need to show how under- and over-exposed images look like or how histograms look like? I don't think so.

 

You see the problem with trying to learn it from reading pages n pages of a foreign language all non related to photography makes it a real drool. But if someone were able to explain it, someone that actually uses them would be simpler because youd put it in plain english and maybe relate it to photography instead of technoze geek.

 

Im pretty good at film n really enjoy my darkroom... I should have been a vampire, I love the dark n late hours.

 

Personal examples of your stuff before n afters maybe demo the adjustmets? That would be nice n really help us noobz understand whats it all about. Id love to see this converstaion moved to DIGITAL DARKROOM as a tutorial if youd be willing?

The more you say, the less people listen.
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I spend more time looking at pictures than graphs, but graphs can sometimes tell you if some parts of your picture are getting clipped (going over or under the displayable brightness range) during processing. If thats a very small area in the image, it may get unnoticed while viewing on small monitors, but may be revealing in large displays or prints. Thats just one benefit I find in checking numbers. The other benefit is, if the brightness of the image pixels are concentrated over a smaller range and not well distributed across the 8-16 levels that the jpeg or tiff provides, histogram can tell you that, while eyes sometimes get deceived. Redistributing the brightness over the larger range improves contrast and visibility of darker areas, and in general improves the quality of the image. Usually I use the histogram as a supplementary guide in my visual inspection of an image, but not as a substitute for looking at the image.

 

I will find some examples later on.

 

Is there some standard those histograms should fit when attempting to make adjustments? See thats the confusing part. Yeah Ive seen these histograms but have no clue what Im looking at.

 

Yes examples would be nice, thanks.

The more you say, the less people listen.
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Personal examples of your stuff before n afters maybe demo the adjustmets? That would be nice n really help us noobz understand whats it all about. Id love to see this converstaion moved to DIGITAL DARKROOM as a tutorial if youd be willing?

 

I'm not going to reinvent the wheel. I could not possibly do any better job than what has already been done by others. Educational material on the subject of histograms is readily available. For instance, search for "how to use histograms in photoshop" on the internet and you will find oodles and oodles of videos and articles. This subject is very basic digital photography 101. If you read anything about RAW converters for instance, you should get a healthy dose of histogram information.

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Is there some standard those histograms should fit when attempting to make adjustments? See thats the confusing part. Yeah Ive seen these histograms but have no clue what Im looking at.

 

Yes examples would be nice, thanks.

 

Follow my advise and read books, videos and articles and you will learn a lot from some very knowledgeable people.

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This subject is very basic digital photography 101. If you read anything about RAW converters for instance, you should get a healthy dose of histogram information.

 

 

if it was photo 101, then why such a problem explaining it?

 

ive spent 50 years and made a nice living from film photo 101 and none of this histogram stuff makes any sense to me.

 

perhaps id have an easier time explaining densitometry n zone system to a noob so i cant understand your constant refrence to books n whatnot. id rather hear it from someone with hands on experiance i can talk to here, whereas books cant answer my questions when it starts the mumbo jumbo 3 letter words that arent even english.

 

here is a photo directly out of the camera. i looked at the histograms n to me it says nothing. maybe you can demonstrate what i should be looking for?

 

canon 20d full sun 1/2 stop under.

 

 

IMG_9012.jpg.4b7ccc3fecb3945ba1ddafa6388365b9.jpg

The more you say, the less people listen.
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Is there some standard those histograms should fit when attempting to make adjustments? See thats the confusing part. Yeah Ive seen these histograms but have no clue what Im looking at.

 

Yes examples would be nice, thanks.

 

I have tried to give one example here.

 

The first shot is straight out of the camera. here I used some exposure compensation to avoid overexposing the bright boat in the dark background, but probably that was too much, as the first photo seems a little dark. The histogram on the right also reflects that, as you can see, out of 256 brightness levels, the image only extends upto 200. In most cases, an optimally exposed shot should have the histogram extended all the way to the right.

 

To correct that, I move the right slider to where the tail of the histogram is. This readjusts the brightness values in the image, so the brightness is more balanced across the entire range available to the display/editing software. Before, all the brightness values were more concentrated to the left making the image darker. The result and the corresponding histogram setting is shown in the second image. The histogram helps me to decide where to move the slider to get the best contrast in my image without clipping off the bright areas in the boat. If I move the slider too much to the left, the image will have ugly washed out patches.

 

You can probably achieve a similar effect by adjusting contrast and brightness settings in Photoshop, but displaying the image on a bright monitor can sometime deceive the eyes, when you try to do that without the histogram visible. Histogram allows you to compare the brightness values of your image against a standard range (0-255 in case of Photoshop) and apply the corrections optimally. This is how I use histograms in my processing.

 

Untitled-837.thumb.jpg.a5758f7dafae0a634bc39a841a94ed94.jpg

 

Untitled-838.thumb.jpg.25a8c2938a7345e9daf7a21a2726d99e.jpg

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In the second example, the image looks washed out and both sides of the histogram needed adjustment.

 

Untitled-839.thumb.jpg.7a6c78038a3d2de6e380ccf5ee8b435f.jpg

 

Untitled-840.thumb.jpg.88440f26b6e820f02849f7fe4eefeeff.jpg

 

I have not talked about the middle slider which is to adjust the middle or average grey tone in the image. If after adjusting both ends of the histogram to where the tails of the histogram end, you feel the image is still too dark or too light, the middle slider can be adjusted to correct that.

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if it was photo 101, then why such a problem explaining it?

STEM Deficiency Syndrome.

 

An histogram is nothing more than a count (normalized) of pixels at each of 256 (8-bit) levels in the image - 0 is black and 255 is white. The histogram may represent luminosity, or any or all of the component RGB colors. You would like to see the histogram taper off nicely at each end of the scale. Too many at 0 or 255 means the image is over or under exposed and there is no detail in those pixels. In a low key image, the mode (peak value) is lower than mid range. A high key image is the opposite. The mode doesn't have to be centered to represent a good exposure, it just shouldn't spill off the ends. An "average" scene taken in daylight tends to be centered.

 

"Normalized" means the count is typically rendered on a basis of 0-1 or 0-100, as a fraction of the total number of pixels analyzed.

Edited by Ed_Ingold
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ive never used it but im only shooting digital for 6 years. i have no idea how histograms work. ive been shooting film all my life.

 

i wish someone would explain how looking at graphs rather than the picture makes any sense?

 

With film, you want the exposure within the range that the film works for.

 

For negative films, it low exposures will be clear, and high exposures very dark.

 

For digital, there are also upper and lower limits, and you want to stay between them.

 

In the usual case, it should be sort of peak shaped, going to zero on either side.

Keeping the peak sort-of centered, so it is mostly zero on both ends is the quick explanation.

As others note, there are more complicated ways to use it.

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-- glen

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(snip)

 

Yes, you can make the argument that if you look close enough, you don't need no stinking histograms. Can you really judge your expose when looking at a small LCD image on the back of your camera, in full sunlight? Can you really stay within the dynamic range of the work space when editing? IMHO the histogram is a very powerful tool and it's up to you to make the best use of it. If you are perfectly capable of taking perfect shots and do a perfect job of post-processing without using histograms, more power to you, but many, less perfect people would benefit from using histograms, both in the learning phase and execution phases of photography.

 

The reason amateur photography has existed for way over 100 years now, is that most of the time you don't.

 

A scene well lit by the sun has a dynamic range (the difference between darkest and lightest) easily within the film range, and even with some latitude for exposure error.

 

A scene half in direct sun and half in the shade is much harder, for both film and digital.

 

Average reading exposure meters work well for average lit scenes.

 

For not so average scenes, they expose mostly for the well lit parts.

With the histogram, you can see what the camera is seeing, both in the well lit, and also less well lit, regions.

You can select the exposure that is the best compromise between light and dark.

 

Or you can avoid such scenes, and not have any need for one.

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-- glen

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With film, you want the exposure within the range that the film works for.

And that range is described by the characteristic curve of the film - exposure vs density.

 

If you can't express it as an equation or a graph, you're faking it ;)

 

(That was in the opening remarks for a course in the physics of sound, according to my wife, a music major. That was an epiphany for her. Mine, as an unrepentent STEM student, was a sociologist professor saying "Sociology has nothing to do with common sense!" A lot of musicians do very well by faking it. Sociologists too.)

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One example of a great explanation of what a histogram is and how to use it is the Adobe Photoshop Elements 2018 Classroom in a Book, available from many sources at about $25 and up. Pages 102 through109 have a chapter called "Recognizing what your photo needs" and talks about "Understanding the histogram", "Adjusting levels", "Assessing a photo's color balance", "Working with the Temperature and Tint settings", "Consulting the color histogram" and "Adjusting the white balance".

It explains step-by-step, in clear language and shows histograms, how to interpret them and what it means for editing. This is one of the best Adobe publications I've ever seen.

 

I couldn't possibly begin to explain this stuff any better.

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I shoot Raw so I always use the camera's histogram when shooting high contrast convection cloud scenes to prevent clipping highlights that proper exposure (or expose to the right) will not guarantee.

 

Clouds have varying intensity throughout their entire shape that the eyes can't see so I back off in this area by underexposing which puts ALL the cloud highlights in the 1/4 zone within the right side of the histogram and Raw converter histogram. I never get blown out blobs of 255RGB white viewing the Raw converter preview processing in ProPhotoRGB color space.

 

It's been working great for me using the histogram this way processing over 1000 Raw images.

Edited by Tim_Lookingbill
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I shoot Raw so I always use the camera's histogram when shooting high contrast convection cloud scenes to prevent clipping highlights that proper exposure (or expose to the right) will not guarantee.

 

Tim, as far as I can tell, you are applying ER to the letter; exposing as much to the right as possible without blowing any highlights and using the histogram in the process. Textbook approach!

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