More on blending images
2008-04-18 by Richard Smallfield
Hi, I just replied to a query regarding a post a fortnight or so ago on image blending and thought it might be useful to post the reply here as well. There are a couple of points: 1. For a less extreme effect, you can go the opposite route, which is to load the channel of the *darker* photo and copy that selection over the top of the lighter frame, thus covering the blown highlights. 2. You may wish to adjust the opacity of the top layer to reduce the effect of blending the two images. You may also want to use a curve to correct the washed out look. The exposure different between the two frames is also a factor - if it is too great, there will be an unnatural effect - I often bracket one stop apart. If you have more than two bracketed frames, you may get a more natural effect by repeating the procedure with the bracketed frames stacked on top of each other. I suggest starting with the lightest exposure as the background and the darkest exposure uppermost, probably with each at half the opacity of the layer below. Adjusting the opacity of the different layers will change the overall effect and it will be necessary to experiment with this. When you select the RGB or Greyscale channels from the channels palette, it selects levels 128-255 - ie: the brightest half of the tonal range. Inverting that selection selects the darkest half of the tonal range - ie: levels 0-128. (Not 1-128 as I said earlier.) This detailed selection based on luminance is very useful in blending bracketed images. Richard At 04:26 p.m. Wednesday 16/04/2008, you wrote: "Very easy - if you have two bracketed exposures, open the darker image. Then open the lighter image. Go to the channels palette and select load channel as selection. Invert the selection. Drag the inverted selection (which will contain a very detailed selection of levels 0-128) onto the darker image - the darker image will remain the background and the new 'layer 1' will contain the darker tones from the lighter image." -- http://smallfield.vze.com "Nothing determines who we will become so much a those things we choose to ignore." --Sandor Minab