Digital Graduated Neutral Density Filter

Hi folks,

long time ago I was using a tutorial which enabled me to created 1 properly exposed picture from 2 pictures (one overxposed, one underexposed) simulating in this way graduated neutral density filter. All could be done in Photoshop. As I am not able to find this tutorial, would like to ask somebody, who came across with this tutorial to let me know where I could find it.

I remeber it was in a PDF file and one had to use some layers created from those two pictures which enabled the picture not to be only horizontaly or verticaly split in 2 diferently exposed parts, but it could be quite unequally divided, and still one could get a nice picture.
Thanks for your help in advance.

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daniel.

Digital Graduated Neutral Density Filter
http://www.ronbigelow.com/articles/neutral-density/neutral-density.htm

Could this be it?

Ron Bigelow has some great tutorials for on a variety of topics.

--
RichO
http://www.pbase.com/richo
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http://luminous-landscape.com/tutorials/digital_split.shtml

http://www.lewiskemper.com/PDFs/DigitalGraduatedND_7_01.pdf

http://www.msjphotography.com/tips/pdfs/Simulating-a-GND_CS2web.pdf

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RichO
http://www.pbase.com/richo
http://www.pbase.com/richo/txwildflowers

The basic method is just to:
1. Duplicate the layer.
2. Darken the new layer as needed.
3. Add a mask to the darkened layer.

4. Apply a graduated shading to the mask on the darkened layer - the transparency of the darkened layer will be graduated based on the mask.

I like to do the same thing to create vignetting or other odd shaped darkening effects to highlight the subject.
--
Jeff Peterman

Any insults, implied anger, bad grammar and bad spelling, are entirely unintentionalal. Sorry.
http://www.pbase.com/jeffp25
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HDR - High Dynamic Range is another approach which uses two images and blends them together using the HDR plugin in PhotoShop CS2. This is different than a simple GND filter using a mask. The images must be significantly different in exposure or the HDR plugin will not succeed.

http://www.naturescapes.net/072006/rh0706.pdf

http://www.cambridgeincolour.com/tutorials/high-dynamic-range.htm

http://www.luminous-landscape.com/tutorials/hdr.shtml

http://www.adobe.com/designcenter/photoshop/articles/phscs2tthdrmrg.html

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RichO
http://www.pbase.com/richo
http://www.pbase.com/richo/txwildflowers

Applying a gradient mask is certainly one approach - but it can't cope with extremes of dynamic range. I think the technique in question here is to use two exposures, one for highlights and one for mid and dark tones, and combine both exposures. It is essentially an HDR technique.

This can be done with two completely seperate exposures, which obviously requires some advanced planning and a tripod. However this technique can also be used to take advantage of the extra DR latitude in raw images that most DSLRs have. The same image is converted from raw twice. Once optimising conversion for the highlights, and once optimising conversion for midtones and shadows (or you could even make three conversions). The conversions are then combined as layers and the appropriate parts of the top layer erased to let the layer below show through. To gain the greatest advantage from this second method (i.e. two conversions from raw) you need to "expose right" so the highlights are as close as possible to the right side of the histogram - in fact ideally so they are just a little over, leaving highlights that would be blown on a jpeg, but can be retrieved from the raw file. I think getting the initial exposure right needs a little bit of experience.

Great tutorials there. I think that might be what the OP was after.

Great tutorials

Many thanks to all of you, that was what I was looking for.

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daniel.

Here's the original.



With a simple linear mask, painted black at the bottom (so little image shown) graduated to white at the top (so the dark layer shows), with the subject cut out (crudely) from the mask so the gradient darkening only applies to the background.



Here it is with a circular mask:



Or with the mask color inverted:



Or with something a little more creative:



--
Jeff Peterman

Any insults, implied anger, bad grammar and bad spelling, are entirely unintentionalal. Sorry.
http://www.pbase.com/jeffp25
http://www.jeffp25.smugmug.com

--
daniel.

Instead of copying the original image, darkening it, etc., you could start with two images - either taken with different exposures and the camera on a tripod or two different extractions from the RAW file. You can then overlay one on top of the other and apply a graduated layer mask, with appropriate selections/deletions.
--
Jeff Peterman

Any insults, implied anger, bad grammar and bad spelling, are entirely unintentionalal. Sorry.
http://www.pbase.com/jeffp25
http://www.jeffp25.smugmug.com