Photoshop Digital Darkroom - Dynamic Range

Before doing anythng in Photoshop it needs to be said that there is always more than one way to skin a cat! Photoshop is such a versatile tool that the same effects can often be achieved in multiple ways. This is one way I adjust the dynamic range of a photo before publishing it.

I have mentioned before that I often under expose a photo deliberately. You can often under expose a photo and lighten it better, without losing too much or introducing too many artifacts, than you can if you try and correct an over exposed photo which often proves to be impossible. This is a photo straight off the camera of an old Bourbon I have called 'Vivid'. Its focus and colour are right but it is too dark as it is.

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One reason I often under expose is that I find my camera renders the colours more faithfully this way. The colours of 'Vivid' are very hard to capture correctly any other way.

The first step in increasing the dynamic range is to duplicate the background layer by opening the layers control and pressing control J (for a PC... not sure of Mac controls).

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Once you have duplicated this layer you need to invert it. Control i will do this.

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Don't panic! You haven't ruined it. Now you need to open Hue/Saturation (control u is the hotkey for this function), and push the saturation all the way to -100. What you doing is taking all the dark parts and making them light to their opposite luminisity; you are making a black-and-white negative of the image.

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Now we need to change the blending mode of this layer to overlay. What you are doing is changing the balance between light and dark and making the dark parts inversely light and the light parts inversely dark.

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At this point the image can look a bit strange but don't worry too much because this can be fixed by applying a Gaussian Blur. I use a 250 pixel Gaussian Blur by default.

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The image looks much better now. The only thing left is to adjust the opacity of this adjusted layer to suit. I prefer it a little less bright so in this case I backed off the opacity to 86%.

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You are now finished and can flatten and save your image.

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This is the finished image with a smart sharpen applied to it.

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The thing I like about this strategy is that dyanamic range can be corrected without actually changing the colours. It should be noted; however, that it doesn't work for all images. It works poorly for images that are over bright to begin with but sometimes works where you want improve the exposure of the background without blowing out the white flower in the middle, for example, if you exposed for the white flower leaving the background excessively dark.

Have fun trying it

Thanks Simon
Easy to follow instructions, and it is certainly a problem with dynamic range quite often. When you underexpose, do you have a particular bracketing setting you use most of the time or do you have to judge by instinct and experience?
Do you generally shoot with a tripod or hand held? I gather you use ISO 100 as your standard setting?

I'm going to print off your ideas from yesterday as well as this to follow. I really hadn't thought of spot metering and must look up the Nikon book to work out how to change the metering on my camera.

I still haven't got my head around layers fully, and think I need to just do it without worrying about grasping some of the ideas behind them. I bought a couple of good books that take you through the basics of Photoshop, but haven't yet gone in really solidly. (Gaier and Andrews, Anon and Grey)

Thanks again

Lili

LiliB wrote:When you underexpose, do you have a particular bracketing setting you use most of the time or do you have to judge by instinct and experience?
Do you generally shoot with a tripod or hand held? I gather you use ISO 100 as your standard setting?

Only time I have ever shot rose with a tripod is when I was using the reflectors and then the flash/reflector was on the tripod and not the camera.

When I under expose what I do is use the camera's in-built exposure metre to set the camera to what the correct exposure would be and then adjust increase the shutter speed until I reach 1/60th of a second so i don't get shake-blur with the hand-held camera. If its too big a drop in exposure (using the camera's exposure metre as a guide) then I don't worry about it because it will be too dark to be useful. I only ever use ISo 100 because at higher settings I get bad noise artifacts in my images. My dSLR is the first Canon dSLR to come on the market and needs upgrading.. will need to sell a few more roses first though

Well it is Christmas Simon and I think you deserve a new camera from Santa.

With your skills I think it is a necessity not an indulgence. Anyway, I will give all this a go in Photoshop. It looks straightforward.... Thank you taking the trouble to post it.
Chris