How to show what it would have looked like without flash?

Hi all

I have somehow been talked into doing a slideshow of my diving pics after a dinner next week. I have 15 minutes. It's a gathering of a professional society (of actuaries), and I'm part of the entertainment. I think it's the first of a series of "what actuaries get up to when they're not exercising their professional judgement" talks. (No need for any smart comments, thanks! Let's keep the board clean.)

There's no particular reason to suppose the average actuary here knows anything much about diving. It's all very well showing pics of all sorts of things, but I'd also like to point out that some of these gorgeous critters don't look so brilliantly coloured in natural light. However, I have no good examples of natural light (with or without approriate white balance) vs flash exposure of the same scene. I'd particularly like to be able to point out that some things which show up brilliantly in the pictures are really hard to spot in natural light.

I tried reducing the red channel in photoshop, but I didn't seem to get what I wanted. Maybe I was doing it wrong. Or maybe it's impossible to give an accurate impression of what things look like in conditions of very low red light levels, but with the eyes adapted to those conditions.

Does anybody have a reliable method of doing this, suitable for a not-very sophisticated Photoshop user such as myself? I'm willing to mess around for a while adjusting settings, but I don't yet know which controls I need to play with.

Any thoughts appreciated.

Thanks

-David

Hey David,

The characteristic look comes from (1) lack of reds, (2) poor contrast, (3) heavy green tint to whites, and (3) really bad blacks. You need to raise your blacks well into the grays and tint them heavily cyan then suck out red. First you should probably lower contrast and saturation. Then, using levels, adjust the red, green, and blue controls independently and adjust the ouput levels slider at the bottom. For red adjust the high value way down. For green and blue raise the lower value from 0 to a hgher number. You'll have to do this by feel. You could also use the channel mixer to achieve similar results and to blend a lot of the color detail away.

Hi Craig, thanks for the explanation - there's a lot more to it than I first thought of. Will start experimenting now ...

-David

Thanks again, this seems to produce quite realistic results, for 2 versions:

(1) what it's actually like down there at around 10m depth, for eyes adjusted to land conditions, which I can confirm by comparing with pictures taken with my old Sony P5 a couple of years ago. I can get there on average (or close enough for my purposes, for green water conditions) using approximately saturation -50, levels (red output range 0-63, blue 32-223, green 64-255), contrast -40 or so.

(2) what it looked like when I was there, with my eyes adapted to the conditions, which I can get to using similar settings to the above except that red range is 0-191. Of course I'm relying on my memory ...

The difference between the two is the adaptation of the eye ...

Just confirms that there really is no right answer as to what is the "correct" colour for most of the things I see in those conditions, because the eye's adaptation fools me.

-David

In Photoshop CS go to Image to Adjustment to Photo filters. Pull down photo filters. The last one is Underwater. Alternatively someone posted a free link to a photoshop action that you can download and load in actions. I've used this one on an image that someone sent me that was shot without a flash.