graduated ND filter obsolete with PS and 2 images?

[walterh]

hello,

in the photography of e.g. landscapes the use of graduated ND filters

is often used to decrease the brightness of some areas of the image

like the bright sky. is this still a good way to go or will

superposition and merging two or more images taken at different

exposures yield superior results? (in the field grad ND filters can

be a pain.)

 

i tried some merging of images in PS but it seems more work than to

use the filters - or is it just a matter of practise? any good links

to a practical workflow?

 

any experience , perhaps examples?

 

cheers walter

[nicholas_rab1]

Unfortunately I do not have anything nice for an example, but this technique is what you make of it. I have spent anywhere from 2 minutes to many hours on one image. The workflow I use for a quick and dirty graduated ND look is this:

 

Get both of your images into two layers, then use the gradient tool as a mask with the top layer. Hold the ctrl key in order to make it perfectly horizontal. Depending on how far you pull the gradient you can make a hard or soft transition. This actually gives a similar look to an actual filter, rather than the more tedious select masking which can look more realistic.

 

Make sense?

[walterh]

thats about what i tried. but how do you get a non linear effect in just the right way? what about color adjustments? that gave me most problems. color correction in areas of different light were tough to look well adjusted and "in tune" between the diffent light areas (as always in direct light/shade anyway).

[nicholas_rab1]

Well, I think the key idea here is be subtle. Your images should not be more than a couple of stops different otherwise there is no way it will look good. Also, just like with a filter, some shots will work well and others will be obvious when you alter them.

 

As far as color correction, you should be shooting RAW (or the nikon equivalent) and using the same white balance. Don't do any levels or other color correction until after you have done your masking. If you are doing all of this and still getting big differences in color I am not positive I can help. Maybe post a res'd down copy of your merged file?

[jean deaux]

There are many ways to reduce contrast in your digital images:

 

1) Take 2 images--one exposed for the highlights (H), and the other for the shadows (S). Open both images in PS, and paste (H) on top of (S). Use the eraser tool to erase anything that is overexposed, so parts of the (S) image starts to show through (be sure to use various sized brushes to get all of the nooks and crannies). This is a very easy method, and will give you a non-linear ND grad effect.

 

2) Take one photo exposed for the shadows, and open in PS. Select the highlights with whatever tools you'd like to use (the magic wand works well--use various tolerance levels, and CTRL click to add to your selection. Feather the selection (anywhere from 2-5 pixels work well, depending to the resolution of the image). Copy the selection and paste it into a new layer. Double click the new layer to bring up the layer properties, and select "Multiply." At this point you should see your highlights significantly darken with excessive saturation. Go to your layer properties again, and play around with the Opacity slider until you get your desired result. You can also play around with the saturation of the pasted layer.

 

3) Contrast masking--Open your image in PS. Copy and paste the image into a new layer (i.e. 2 identical layers). Select the top layer, desaturate the layer, then invert the layer. You should see something that looks like a black and white negative at this point. Double click this layer and select "Overlay" from the pull down menu. At this point, you should see a very flat looking image. Use the opacity slider to get the desired effect. This is an effective way to reveal shadow detail. You can also use the eraser tool to erase any areas of the top layer that don't need any contrast adjustment.

 

There are a number of other methods, but try these methods first. Every image benefits from different techniques, so play around with these. The first method is by far the easiest, and it's very effective.

 

Hope this helps.

[greglyon]

It's definitely an art! Here are a couple links that I've found to be helpful:

<p>

<a href="http://www.luminous-landscape.com/tutorials/digital-blending.shtml">www.luminous-landscape.com/tutorials/digital-blending.shtml</a>

<br>

<a href="http://www.luminous-landscape.com/tutorials/blended_exposures.shtml">www.luminous-landscape.com/tutorials/blended_exposures.shtml</a>

<p>

Sometimes this single image trick works better:<br>

<a href="http://www.luminous-landscape.com/tutorials/digital_split.shtml">http://www.luminous-landscape.com/tutorials/digital_split.shtml</a>

[jean deaux]

When I shoot film, I usually carry around my ND grads. But with my dSLR, I usually leave them at home. You can usually get a better result by combining two images (or manipulating one) in PS than you can using a ND grad. It just takes time to develop the skills for it to an efficient method. However, sometimes it's not practical to take two different exposures. Examples of these situations include fast changing landscapes (fast clouds, tornadoes, surf, windy conditions,...), action shots (moving wildlife, car racing, flying aircraft...), candids, and a number of others. These types of situations are often best shot with the use of a ND grad (as opposed to combining 2 exposures--you can still use methods 2 and 3 above). Especially if you set the camera on a tripod, set up your ND grad, and are waiting for that "moment" to trip the shutter.

 

But I still prefer the digital method over the use of filters. I heard a philisophical argument that said that a photograph should be a "moment in time"--by that reasoning, 2 exposures are "2 moments in time."

[zapped]

Yes, PS & two bracketed images is <i>better </i>than a grad ND.

You don't even need two images - if you shoot RAW at an intermediate

exposure, you can output a +1.5 and -1.5 stop version and combine those.<br>

<br>

Similar thread <a

href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=0073eZ">here</a>.

[dan_lovell]

Well, for those that only want to worry about taking one image, there is always the history tool. Here is how it works, go to your levels in image adjustments, play around with the levels or any adjusment for that matter until the sky becomes what you want, then simply use the history tool on things that you didnt want to change. the history tool can be used with any combination of events, and with anything you work with, for the sake of having something to go back to, take many history snapshots, so that if you mess up, and undo wont bring you back far enough, the snapshot is there as a "safety." I would use the history brush after making the appropriate adjustments to the sky, use the history brush only on those things that you want to come back to the original and as always it is best, in my opinion, to work with the RAW format. Just remember, there are a million different possibilities for the same or similar result, i just find that if you use the magic wand and select just the sky, the result leaves things a little blocky if you dont take the time to go in and thoroughly select every part of the sky. which can also become tedious with the history brush, but for most of my applications, this seems a fast and easy method. -"Slowness"

[link]

I shoot with a fuji 6x9 rangefinder and it's impossible to position a grad without

seeing through the lens.

 

My solution is to shoot negative film. The exposure latitude is so great that I can do

my "grads" in photoshop.

 

Here's an example:<div></div>

[beno_t_marchal]

<p>If you have a digital camera (I'm told aligning scanned photos is a lot of tedious work)

then PS is dramatically more flexible than an ND filter because (1) you can bracket more

(you are not limited to two photos, you can use 3 or 4 exposures) and (2), most

importantl,y you can work around odd shapes such as flowers or columns in the

foreground that overlaps part of the background.

<p>It does not take more time in the field to take the two photos than to use the ND (you

would probably bracket with the ND as well anyway). As long as you are merging along a

straight line (as an graduated ND filter would), it does not take much time in Photoshop

either (make a gradient, superpose the two photos, add a mask, put the gradient on the

mask and you're done --if you save the gradient as a preset, next time it will be even

faster).

<p>Granted if you want to merge a flower against a background then it takes a lot more

time to build the mask <b>but</b> now we're talking of something you could not

achieve with an ND filter so a comparison is meaningless.

<p>One word of warning: make sure you're in aperture priority when you bracket or the

two images may not superpose well.

<p>--ben<br><a href="http://www.marchal.com">marchal.com</a>

[walterh]

thanks for the helpful contributions and sorry that i respond so late. im on a longer trip so quite difficult to get back to you all.

i will bring lots of PS work, including bracketed images to combine. so i hope this will all work following your suggestions.

cheers

walter