Histogram?

[Xavier]

I want to know how many people here religiously use the histogram? Pro photographers all around the world swear by it, and it has been seen as one of the great discoveries of the digital era of photography. I love using it and have been using the ETTR (Expose to the Right) method lately for an improved signal to noise ratio and the difference is certainly noticeable.

[MG_1806]

Discussion Approved

[anvancy-(macro analyst)]

it is an integral part when you shoot.its ur guide for the light that is falling.you can also check which metering should one apply for a particular shot.since when you change your meter from avg to spot,the histogram also changes invariably telling that this shot may be overexposed.

certainly a vital feature.

anvancy

[Bibudesh]

Its a must check for me these days since I am using RAW 100% of the times. Earlier I seldom use to check them while shooting jpegs.

Sometimes you can predict the histogram before opening them only.

[rio008]

personaly i do not use the histogram, but when i transfer my images to CS4 first of all editing i do use LEVELS to make the currections like under/over explosures. :)

[synn]

Always use them; be it while shooting or making HDRs. Learning to use the histogram properly takes you a giant leap closer to always achieving perfect exposure.

[rio008]

but how to understand looking at a histogram and to know its over/under exposed ?

[Xavier]

Its a must check for me these days since I am using RAW 100% of the times. Earlier I seldom use to check them while shooting jpegs.

Ditto.

Always use them; be it while shooting or making HDRs. Learning to use the histogram properly takes you a giant leap closer to always achieving perfect exposure.
So damn true!

but how to understand looking at a histogram and to know its over/under exposed ?
Check the extreme left and right part of the histogram. There should be no spikes touching the edges. These are the parts where the image is underexposed(left)/overexposed(right). Whilst shooting in RAW, one should always see to it that histogram is biased towards the right, but be careful to not clip highlights since these cannot be recovered. This method is known as ETTR (Expose to the Right) and using this method one can achieve good Signal to Noise ratio, thereby reducing noise.
This is contrary to the normal method of deliberate underexposure so that one can boost the exposure in PP later. This method introduces a lot of pattern noise in the shadow areas.

[Xavier]

Check this link (http://www.cambridgeincolour.com/tutorials/histograms1.htm)

There's no 'perfect' histogram. Each scene will have its own optimum histogram.

[Vicky]

Check this link (http://www.cambridgeincolour.com/tutorials/histograms1.htm)

There's no 'perfect' histogram. Each scene will have its own optimum histogram.

/\ This is why i hardly ever refer to the histogram:)

[Xavier]

/\ This is why i hardly ever refer to the histogram:)

What about clipping highlights?

[drsureshmohan]

In the link below is a good discussion of the histogram http://www.astropix.com/PFA/SAMPLE3/SAMPLE3.HTM
if u need to clarify details on how to modify a histogram i can help, just let me know. It is all about adjusting leves and curves in individual colour channels to get closest to the real image.
Kindly note that the above relates to astrophotography and the same principle is applied elsewhere ;we also need to know about white balance because in our cameras the IR filter is removed there will be too much red, so we use a gray card for white balance(custom) and here you can learn what modifying curves does http://www.marginalsoftware.com/HowtoScan/changing_brightness_and_contrast.htm

Suresh

[Xavier]

Nice link doc. The only thing I'd like to add is that too much of levels/curves adjustments can cause spikes in the histograms and thereby leading to Image Posterisation since the image's bit depth is decreased by those adjustments.

[drsureshmohan]

Yes posterisation occurs when too much levels or curves are applied but if u watch the histogram while making the adjustment it would be fine
Suresh

[Daniel Browning]

I want to know how many people here religiously use the histogram?


I do. That's why I am very annoyed that manufacturers do not offer a raw histogram. The histogram only reflects the preview JPEG, which often has very little similarity to the actual raw histogram. That's why I use the UniWB workaround, as explained here:

http://forums.dpreview.com/forums/read.asp?forum=1037&message=26905476