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Using PS to gain Dynamic Range (3 img)

PostPosted: Sun Dec 11, 2005 12:26 pm
by Aussie Dave
Following from THIS thread that Owen posted a few days ago, I have been going back over a few photos, using the process described in the previous thread, to obtain better dynamic range, using multiple photos (or the same NEF but processing it twice with a dark and a light version).

The results I achieved are:

1.
Image

2.
Image

3.
Image

I'm not 100% sure if this method actually gives you more dynamic range, or if it just gives the illusion, however it does seem to make quite some difference.

Has anyone else tried this method and what results have you had ?

PostPosted: Sun Dec 11, 2005 12:43 pm
by kipper
Which method in PS? Did you have 3 layers and use and eraser to reveal the layers underneath or?

PostPosted: Sun Dec 11, 2005 12:48 pm
by avkomp
like the first 2.

were these done with the merge to hdr function??

Steve

PostPosted: Sun Dec 11, 2005 2:26 pm
by mudder
G'day,

Love that first one, looks great!

I use a similar method, (detailed below) to achive a significant boost in the DR available in an image... I use it mainly on landscape stuff (stuff that doesn't run away or move etc) and find it terrific for improving DR in the final image without pushing up shadows and noise etc. Using two or three images with a spread of 1 to 1.5 stops.

I tried HDR but only used 3 images and didn't give me anything better than the quick hack below, which seems to work a treat and you can play with the mask at the end...

A combined image using the hack:
http://www.pixspot.com./albums/userpics ... 7%20v3.jpg

Technique: Sounds convaluted but once you've done it once or twice it literally only takes a few seconds:
1) open both the low exposure and high exposure images,
2) make the low exposure image current
3) ^A (to select all) then ^C (to copy to buffer)
4) make high exposure image current
5) ^V to paste the low exposure image into the high exposure image
6) Go to layers, make sure the pasted low exposure layer is current
then make a mask but clicking the icon that looks like a camera from
the front (didn't know how else to explain it...)
7) Alt-click on the mask window (the white window in the pasted layer
pallette) This should give you a white screen/image
8) Then paste into the white screen, this should give you a black and
white image
9) Then just click on the background layer to make it current and hey
presto! Merged exposures...
10) Then you can make the mask layer current and hide the background
and clean up erasing any bits of the mask you don't want...

PostPosted: Sun Dec 11, 2005 2:39 pm
by Aussie Dave
This method works by having two different exposures of the same image (or the same image converted differently from the NEF - one lighter & one darker).

The process is:
- The dark version is pasted as a "new layer" on top of the light version.
- With the darker layer selected, press Ctrl + Alt + ~, which will make a mask/selection of the highlighted areas (from the luminosity channel).
- Then, you select the "add a mask" function from the layers menu (the symbol looks like a rectangle with a circle in the middle)
- this will mask out the darker areas of the "darker layer", letting only the lighter areas to show through.

As these lighter areas have been processed darker than what the same area is on your light layer, (and ideally they are not blown highlights) , they will give more definition to the lightest areas in your "light layer" - giving you, or creating the illusion of, more Dynamic Range.

Sorry, I know I am not explaining this the best. Try it for yourself and you will soon see what the effect is. Once done, try toggling the dark layer on & off, so you can see what difference has been made.

I've played around with stacking 3 or 4 differing images on top of one another, all processed slightly lighter or darker than one another. You can also put the lighter version on top and do it all in reverse as well, which gives a different look again.

Of course, ideally you would use 2 different exposures of the same image (from a tripod), around one stop apart.

PostPosted: Sun Dec 11, 2005 2:46 pm
by mudder
Judging by the process, I think the CTRL-ALT-~ effectively does what I'm doing with the paste into the mask... I usually use differently exposed shots of the same subject taken at least .5 to 1.5 stops apart, eg: bracketed shutter speeds on tripod...

Photoshop's great, there always a swag of way to skin the same cat (ooops, sorry cat people :lol: )