HDR vs. VGND

[eNo]

Check out my latest blog entry, where I feature a technique I've been playing with to use two frames out of a 3-frame HDR bracket to achieve a Virtual Graduated Neutral Density (VGND) filter effect: http://esfotoclix.com/blog1/?p=238

[Dave Humphries]

Hi eNo,

Good idea, but I was hoping to learn HOW to do it, is there a page 2 coming?

e.g. 0EV on Background, +1.3EV on layer 1, Layer mode = ???, brush white (or black?) to reveal background through foreground in sky area.

I've probably got that all wrong, hence I need help.

Regards,

[eNo]

Good point: I'll have to think about a follow-up to work through the editing steps. My concern is that since I use PSPX2, most Photoshop users will have to translate what I write into PS, as I often have to do when I read one of many PS tutorials.

In a nutshell, though, you want the darker exposure image in the background layer and the bright in the foreground layer. Then in the foreground layer, you select the bright sky and delete. Since I don't blend the layers (I forget the right term: opacity=100?), but instead the foreground layer simply covers the background layer, the foreground is bright, minus the bright highlights, with the darker background highlight areas showing through, and voila! I have my composite. Exposing the original images with a tripod is highly recommended to avoid alignment issues.

[Colin Southern]

Originally Posted by Dave Humphries

I was hoping to learn HOW to do it

Hi Dave,

In essence one just needs to use a layer mask - the trick being however to set the brush opacity to something quite modest (say 20 to 30 percent) and something quite soft, so that clicking once on the mask doesn't produce a "hard" result ... it means you can "click here, click there" multiple times to transition the two image more seamlessly.

The other part of the equasion is that often you need to tie various adjustment layers to each image (levels etc) to get the local contrast looking more believeable (eg you may have to drop the levels of something in the foreground so that it's not brighter than something in the background).

[john w revie]

Dave Colin eNo

The same effect can be achieved from a single raw file.
First open a copy of the raw file with the highlights adjusted as required;
To open a raw file as a copy press the ALT key while opening the file;
Next in Photoshop go to file open recent and choose the file at the top of the list
This will take you back to the same file in ACR.
Re-ajust the settings until the shadows are as required open this adjustment as a copy
Select the file adjusted for the highlights select all copy now select the file adjusted for the shadows and paste a copy of the highlights into this at this point you should have a file with two layers Background and layer one.
Make layer one active. Now to produce the mask press (Control Alt 2)
This will select all the pixels in layer one proportionally to their luminosity values
With the selection still active click on the make mask icon at the bottom of the layers
pallet: the third from the left: this will add a complex mask to layer one, invert this mask
Go to filter blur Gaussian blur and set to 50%. This mask can now be adjusted by running levels or curves directly on the mask.
This technique is useful in situation where there is a risk of camera movement if say you are shooting in a fast river or on soft sand.
The same masking technique used with two raw files one properly exposed for the highlights and one for the shadows produces a much cleaner finished photograph.

John

[Colin Southern]

Originally Posted by john w revie

The same effect can be achieved from a single raw file.

Hi John,

What your suggesting works (and works well) so long as the all of the highlight and shadow detail required is captured in that single RAW file (which in many cases it is), although if it's "close" then you'll also have a lot of noise in the shadows. It's a technique I like to use myself as I find it easier than having to use 'extreme' curves etc (although later versions of ACR have made the job a lot easier). Some of my shots are pushing 15 stops of DR though, and there's way to do it in a single shot without using a filter to compress the range.

We had quite a "robust discussion" along a similar vein a little while ago.