A Letter from ColdwaterJohn

My good friend ColdwaterJohn has recommended this article on HDR to me.  I went there and found a very well written basic multiple image HDR tutorial.  Not quite our thing, I know, but we must keep informed.  I was intrigued by this gentleman's (Harold Davis) previous article on using a single RAW image processed in different ways and then combining the versions with a layer mask and a gradient to reveal portions of underlying layers.   I know that that's really off the track of SIHDR but you should go there and read his article anyway.  I'll deal with his HDR ideas in time but first let's explore his ideas about multi-processed RAW images.  In short (but read it for yourself) he describes a basic method of processing a single RAW in different ways (in his example he's correcting for different brightness zones) and then combining these versions in Photoshop.  He takes one image in which the left is underexposed and, in Adobe Raw, he makes a version of that image in which the left is properly exposed.  He saves that first image.  He then makes a second version in Adobe Raw in which the overexposed portion on the right is corrected.  He now has two partially correct images and he layers the bright image over the dark image and then exposes part of the dark image by using Layer Mask Hide All and then erasing part of the mask (the bright image) with a gradient.

A gradient.

Hmmmmm.  It's the old neutral density filter trick but moved way up into post-processing.  There are circumstances in which this approach is effective (Mr. Davis demonstrates one) but for most circumstances it introduces more problems than it solves.  The basic problem is that the neutral density area is simply not the required shape.  Here's an example where something else has to be tried:

In Athens recently S and I went to the Kerameikos which is a kind of ancient cemetery (not far from Plato's Academy) and I made this ghastly shot.

This is a beautiful funeral stele but the shot is totally ruined because I was shooting into the sun so that the temporary roof in the foreground is way too bright and the rest is murky and dark.  A failed shot (Not to boast but I have a built-in advantage as a photo-blogger because I take so many bad shots that I always have something to fix).

Mr. Davis tells us to take the RAW and make a light and a dark version of it.  No sooner said than done.  Here's the light version:

The stele and the background look good but the roof is over-exposed.   Here's the dark version in which the roof will be properly exposed:

...and of course everything else is murk.

Now we put them together.  Of course it's very difficult to design a gradient that will combine these two.  There's a dark zone on the top, a bright zone in the middle, and another dark zone on the bottom.  Mr. Davis' shot had only a dark zone on the left and a light zone on the right.  His shot was made for a gradient.  This one isn't.  But just to show that I'm a good sport I tried it his way.  I layered the light layer over the dark layer and used a layer mask to hide the upper layer until the application of the gradient.    Here's the shot again with a gradient drawn from the upper left edge through the peak of the shadow and ending at the edge on the lower right.

In fairness this looks pretty good.  The shadow of the stele is more realistic than in any other of my versions but the stele sculpture is a little dark and the foreground shadow is way too dark (given that you were interested in it at all which I'm pretending that I am).

For my alternative version I approached this shot in the following way.  I layered the dark layer over the light layer and then I used the history brush in Photoshop to brush away everything except for the roof (and the shadow on the roof - very critical point).  The final result is this:

This is a highly-compressed jpg.  You have to take my word for it that the original TIF had more detail in the roof but I think you get the idea.  The only odd note here is that the shadow seems way too dark for the situation but I'd be interested in what my readers think about that.

In short, read Mr. Davis' article on RAW processing (it reads a little like my tutorial on dividing up an HDR into pieces and using each piece separately) but I'd take the gradient thing with a grain of salt.

Until next time,

Bob