Digital Light & Color

First, I have been away from the computer and Internet for the last 1-2 weeks (5 year old grand-daughter visited from out-of-country so everything, I mean everything, else stopped until she recently departed), so just discovered the latest PWP8 news. Congrats to Jonathan, et al, (if there is an et al) for this. As I am taking up a project I started prior to the visit, I have had little time to download the latest version or review associated documentation. However, really looking forward to that and trying out the new stuff.

Having said that,

I have a couple dozen long-ish exposure (25 seconds) images of flying birds against an overcast sky. Although the background is quite light, it is not pure white. The birds (pigeons) are darker where they are solid and where there is movement (as in wings etc) they gently fade out to the tone of the sky. One of the things I am trying to do is convert each to an 8 bit mask, where the background is pure white (will be later inverted so sky is black).

Each image's dynamic range is a bit away from either end (with the dark end farther away - about 23-ish % and the white end around 97%). These numbers vary a small bit for each image as the images were not taken at the exact same location in the sky and each bird is different a bit in tone/colour.

On the first test image, I started by using Levels and Colour and moving the highlight slider position to 100%. However, when I probed the result, I found the background sky is still not pure white, but a bright greyish tone. I tried pushing the highlight slider a bit more to the right (105%) but still did not reach full white, and any farther, the gradual tone change from bird to background becomes degraded.

So, my questions:

Is there a way to use the Levels and Colour tool to do the above on a first image then use the same settings for the rest, but with only a change at the highlight end? I wish the dark end for each image to remain unchanged (so each image will have it's own dark end tone) and only the highlight end to be the same for all images. As it is now, the tool can repeat the settings from the previous image, but it changes both ends.

As mentioned above, the more I try to get the background sky to be full white, the more the gentle tonal transition ends of the wings etc on the birds turn lighter and lose "volume" (if that's a good way to put it) and recede into the body. I tried making a mask using the Flood Fill tool on the sky area but found it just did not give me that gradual transition around the blurred parts. Can someone suggest a better way to accomplish this?

I'm looking for a workflow that may be used on the multiple images I have to work on, taking into account the difference in tones of each bird and the desire to retain that gentle gradual transition around the edges of the subjects. That graceful transition is important to accomplish. Any comments/suggestions would be appreciated.

Thanks in advance,

Marv

My suggestion requires manual intervention on each image.

1) Convert the original to 8-bit black and white, save a copy, and then carefully clone all the birds and their trails out of the image by copying adjacent sky over them.

2) Invert both images (Transformation/Gray/Invert). This should leave you with two images, one with and one without birds and with the sky dark and the birds light.

3) Subtract the cloned image from the original (Transformation/Special Effects/Difference). This should make the sky black and leave the birds some gray level.

5) Adjust the brightness to taste to lighten the birds

By subtracting the background, you are automatically taking into account any variations it may have.

Holy smokes Jonathan, what a unique suggestion. Can't wait to play with this one.

Sort of figured I would have to do at least a little bit of the manual stuff for each image.

Marv

Just wanted to add a quick follow-up and say Jonathan's suggested workflow has been working remarkably well. Of course, the downside is the number of images that I've had to do this on!!

Marv

Good to hear.

The Speck Removal tool might work a little faster and better than cloning.

I've never used the speck removal tool, so am unsure if it would work on these images as some of the birds that need to be cloned out are quite large (not a typical speck). The image dimensions are 6000 x 4000 and some of the birds (including extended wing/movement blur) are up to a fifth or sixth the image length (so maybe 1000-sh pixels?). Some are smaller at maybe 4-500 pixels. How large a speck will the tool work on?

Marv

Max radius is 1000 pixels