Photoshop Histograms Inaccurate

I've felt that the histograms of underwater photos in photoshop tend to judge properly exposed images to be underexposed. I expect this in blue-water scenes, but even in macro scenes I've found this to be the case. Only in well-exposed bottom scenes with lots of sand (flounders, sea cucumbers, etc.) have I found that the histogram successfully judges exposure. Any comments from other PS users? I use PS 7 on Mac OSX.

Kasey

The histogram is, after all, just data. Population of each of the RGB channels is simply that. A histogram is not weighted based on the perceptual values of those colors. (A properly exposed orange sunset will look brighter than a properly exposed blue water scene.)

It's interesting that you used the word "Judges" when explaining the histogram. Naturally, Photoshop doesn't really "judge" the colors at all.

Daniel Brown

Sr. Evangelist

Adobe Systems Inc.

danielb@adobe.com

http://www.adobeevangelists.com

Kasey,

although the histograms can tell me a lot about what's wrong with a photo, i never use them to judge correct exposure. i usually notice over/underexposure when i simply look at the photo

Sabine

Daniel,

In case I haven't said this before, welcome to Wetpixel!!!!

Our primary tools here are:

1) Digital Camera

2) Underwater Housing

3) Adobe Photoshop!!!!!!!!

I don't know where most of us CCD and CMOS shooters would be without the Unsharp Mask!

Your comments and insight are truly appreciated, so please stick around.

Cheers

James Wiseman

www.reefpix.org

Thanks Jamesw!

Good to be here... My wife and I got hooked a year ago speaking at the underwater shootout events.

(http://www.theshootout.org)

We just got back from Bonaire and the combination of diving and Photoshop are still on our minds.

As for my comments, glad to know they might be of some help. If there's ever a really sticky question, I can always walk up a flight of stairs and ask the software engineers. So even if I don't know the answer, I can certainly find someone who does.

I'll certainly pass along my Photoshop tips in exchange for some idea as to how you guys get sea life to pose for those amazing pictures!

Cheers!

Daniel Brown

Sr Evangelist > Adobe Systems Inc.

danielb@adobe.com

www.adobeevangelists.com

Hi Daniel,

I just got back from a day dive trip where I shot three dives @ 76 fuji RAW images apiece. Information overload!!!!!!

If you guys can make a photoshop plugin for fuji RAF files that works as well or better than Mike Chaney's Qimage Pro, I will buy it in a heartbeat.

Right now my workflow is something like this:

Burn all my RAW's to CD as an archive.

Open the Fuji image browser and pick the RAW files from my hard disk that I want to convert, then convert them as a batch using their Hyperutility LE fuji software.

Open the 12 megapixel TIFF's in Photoshop, then adjust levels, then curves, then USM.

Drop those all in a file then use the Web Image Gallery feature to do batch resizing (images to 600 pixels wide) and thumbnailing.

USM AGAIN on the 600 pixel images and then up to my website.

Man, that is time consuming.

So what did you think of the DSLR shooters at the Bonaire Shootout? Is their output good enough for publication? I think it is but some ppl still think it is up for debate.

What would you like to know about UW photography technique? We can SURELY trade tips.

Cheers

James

Hi again James,

We certainly understand your pain (along with that of everyone who uses higher-end cameras capable of raw formats). Again, can't comment much other than what the press release said and what my Julieanne Kost demoed at the keynote at Photo Plus East.

I hear the distinct sound of salivating going on...

Daniel Brown > Adobe Systems Inc.