dc10tim
Posts: 1380
Joined: Mon Jan 03, 2005 12:21 am

How Accurate Is The Histogram?

Thu Oct 20, 2005 8:42 am

Hi everyone,

I was just wondering when editing, if to get the levels correct, bringing the small triangles in Photoshop to the edges of the histogram actually gave an accurate indication of what was actually seen?

Below is a shot of mine, taken in bright sunlight that for some reason seems a little subdued. Similarly, a lot of my shots from the weekend seem like great sunset shots, or shots taken in low sunlight, but were in actual fact taken in bright sunlight. Is this my imagination, or is there something I'm overlooking that I should be aware of? How do you get "sunny" photos?

http://www.airliners.net/addphotos/big/ready/lzbha2409man2.jpg

Regards,

Tim.
Obviously missing something....
 
eadster
Posts: 2125
Joined: Tue Jan 25, 2005 7:31 pm

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 12:30 pm

Excellent pic Tim.

The way I check is that (and this may have been discussed already) is that if there is flat on the left of the graph, the image is over-exposed and on the right the image is under-exposed. If thats the case, I drag the outer triangles to the edge of where the graph starts. If you get what I mean!

I used to have the problem with different lenses of mine as some pics where coming out dark on bright days. Now I use Exposure Compensation to fix the prob. I still use a lens from film days on my digital. Quality is still ok but thats why I have use exposure compensation.

Other than doing that, in Photoshop, if you go to "image" -> "Adjust" -> "auto levels" it does it for you!

According to my photoshop here, all the levels are ok on your image.

Hopefully what I have said here is right. Someone will soon tell us otherwise!

[Edited 2005-10-20 05:35:39]
 
Jan Mogren
Posts: 2014
Joined: Tue Dec 26, 2000 2:47 am

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 4:18 pm

Tim,
if that shot looks subdued I'm afraid your monitor calibration was not succesful.
It looks very sunny to me.

/JM
AeroPresentation - Airline DVD's filmed in High Definition
 
fergulmcc
Posts: 1877
Joined: Thu Oct 14, 2004 8:36 pm

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 5:21 pm

Quoting Jan Mogren (Reply 2):
if that shot looks subdued I'm afraid your monitor calibration was not succesful.
It looks very sunny to me.

I would have to agree with Jan on this Tim, that is a cracking shot mate, pin sharp, I would be proud of a shot like that Tim.

Fergul  sun 
Zambian Airways, Where the Eagles fly free!!
 
manzoori
Posts: 1459
Joined: Sun Sep 22, 2002 7:08 am

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 5:39 pm

Definitely not Subdued Tim... Jan's right, have a look at you rmonitor as the image looks lovely and sunny to me.

Cheers!

Rez
 Big grin
Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
 
eadster
Posts: 2125
Joined: Tue Jan 25, 2005 7:31 pm

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 6:24 pm

sorry guys, reading that again, I totally misunderstood what was asked and dribbled on.

forget the crap that I went on with there.

 Sad

Quoting Fergulmcc (Reply 3):
that is a cracking shot mate, pin sharp, I would be proud of a shot like that Tim.

Yep I'll fully agree with that.
 
dc10tim
Posts: 1380
Joined: Mon Jan 03, 2005 12:21 am

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 7:51 pm

Quoting Eadster (Reply 5):
sorry guys, reading that again, I totally misunderstood what was asked and dribbled on.

Not at all Martin, what you described is exactly what I do, bringing the triangles into the edge of the histogram. Often I have to increase the brightness of the midtones too.

Thanks to the rest of you. The monitor is calibrated and the colours generally look excellent, it's just I don't seem to be able to get that brilliant contrast of bright sunny days that makes the fuselage look really bright.

Perhaps the shot I linked to isn't the best example. On reflection this morning, it does seem reasonably bright. I'm just wanting to achieve the brilliant contrast that sunny days bring and "bringing the triangles in" doesn't seem to achieve this with all "sunny" shots. This may be how it is in real life, which was really the question I was asking to begin with, if that histogram from left to right is a true representation of what the conditions were when the shutter was clicked?

With the shot below, I have had to massively increase the brightness of the midtones to get it looking anything close to daylight Smile Bringing the triangles in to the edges of the histogram left it looking very very dark. It was only after comparison with Fergul's shot of the same aircraft I realized mine was way off. Even now, I'm not convinced the colour temperature is accurate and brightening it so much has created quite a bit of grain.

http://www.airliners.net/addphotos/big/ready/irish251dub15102.jpg

Tim.
Obviously missing something....
 
Jan Mogren
Posts: 2014
Joined: Tue Dec 26, 2000 2:47 am

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 8:07 pm

Tim,
if you needed to adjust it that way, then probably it was slightly underexposed. You need to have the pixels at the right of the histogram in camera just a wee tiny bit from the edge.

/JM
AeroPresentation - Airline DVD's filmed in High Definition
 
fergulmcc
Posts: 1877
Joined: Thu Oct 14, 2004 8:36 pm

RE: How Accurate Is The Histogram?

Thu Oct 20, 2005 9:02 pm

Tim

I think your shot is ok as the sun was a bit low, especially now with winter comming in, also the air on that day was a little hazy, not the best conditions for shooting in.
This is my version and another to show that the sun was low.
http://www.airliners.net/addphotos/big/ready/251-151005-2-fmc.jpg
http://www.airliners.net/addphotos/big/ready/9v-sfk-151005-1-fmc.jpg

Hope that helps mate.

Take care

Fergul  sun 
Zambian Airways, Where the Eagles fly free!!

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