higher dynamic range

[SgWRX]

is this a bad way to get higher dynamic range in an image?

open an image in raw
open the same image with higher exposure
copy one image on top of the other
use the blending mode 'overlay' and tweak with opacity

is this somehow destructive or something?

[SgWRX]

eh, i don't think i have a good grasp on hdr images. have to do some more reading.

[lostdoggy]

Well you can also either bracket the exposure or do two extreme RAW conversion and merge them together and use vector masking to reveal the bottom layer.

[J Rabin]

...is this somehow destructive or something?

1. You can't do anything destructive to a RAW file. You can make any number of conversions with different settings.

2. There are a wide variety of techniques to expand apparent dynamic range of a RAW image -WHEN- a RAW contains all the photographic information, but it can't be displayed in one conversion. Use the easiest techniques first, like:

3. Pulling exposure and pushing mid tones.
Works on an otherwise strong digital RAW exposure with moderate (½ f/stop+) excess contrast, i.e., slightly blown out highlights. This deceptively simple technique works powerfully, is quick and easy, frequently all an image needs for dramatic improvement, works non-destructively in RAW, and is well documented by Bruce Fraser in his ACR RAW book.

4. Sandwiching two RAW exposures.
There are at least 4-6 different variants of blending techniques, which was subject of your Q. The technique and variants were originally from George DeWolfe, Sr. Editor for Camera Arts, and presented on Adobe’s PSCS tutorials website.

I shouldn't do this, because they are just MY notes, but I have documented step-by-step the two of sandwiching techniques starting on page 6 here:
http://postit.rutgers.edu/uploads/ExposeHiContrast%2Epdf

Let me know if it is useful.
Jack

[jfrancho]

Jack, I like your notes - very similar to mine, except mine are in Excel (don't ask, I tend to complicate things...). Even for myself, a very thorough person, they are great to look and see a different point of view.

[SgWRX]

jack thanks. interesting to see all of those techniques in one place. i think one thing i'm catching on to is there's a lot of different ways to play with an image, just as i suppose there are a lot of ways in a dark room.

[jfrancho]

Oh, and to the OP: a couple of videos:

http://www.steve-perks.com/gfx/forumposts/mergeraw/mergeraw.html

http://www.thelightsright.com/tutorials-video.htm

[J Rabin]

Thanks jfranco & SgWRX.
I know notes are jumbled, but hi contrast outdoor on-the-go is my thing, so dealing with hi contrast (excess SBR) is essential. The goal is getting as right as possible in camera.
Like this last monday. I ended using wall greenhouse poly for diffusion of blue sky above the plant with me in contorted position:

http://postit.rutgers.edu/uploads/Dwarf%5FLily021%2Ejpg

Jack