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Smoothing Large Blotches

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  #11  
Old 01-06-2003, 02:42 PM
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jeaniesa jeaniesa is offline
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Thanks for getting back to us with your solution. I'm afraid I don't have any other great ideas for you. I'll be tucking your solution away for further reference as I'm sure this is not an isolated incident!

BTW, nice image. Did you scan the image yourself or have it scanned prefessionally on a drum scanner? (Just asking because the digital size is quite large for a "typical" scan.)

Jeanie
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  #12  
Old 01-11-2003, 11:23 PM
TheTexan TheTexan is offline
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Im sure this is simplistic since the background sky is probably more complex in the original photo but here on the right side of your blotchy jpg is my duplicate. I simply replicated the exact gradient and it is hard to distinguish from the original. The dithering you see is caused by the jpg compression to put it on the web. It is not present on my computer or on the print.

Tex
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  #13  
Old 01-13-2003, 01:51 PM
kthurner kthurner is offline
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Tex,

How exactly did you do the replication?
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  #14  
Old 01-13-2003, 11:35 PM
TheTexan TheTexan is offline
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The way to duplicate the gradient is like this. (I will use for my illustration a linear gradient, that is, one that would fill a rectangle top to bottom with no curvature).

1. Take the original gradient image and divide the image into several sections using guides. I used a guide every 25% of the image height.

2. Then in the gradient editor place a color sampler at each of the 25% locations.

3. Sample the color for each of the gradient editor color tabs from the corrosponding location on the original image. This is duplicate the gradient in that image.

4. Then simply fill a layer with that gradient.

You can use as many samples as necessary to get a better replication. You will also have to adjust the mixer points between each color tab to duplicate the rate of gradiation change to match the original. However, the more you divide the original image the less important this becomes.

Now if the gradient has a curve to it as would a morning sky with the sun just below the horizon you can use the shear filter to add the slight curve to the overall gradient. To recreate the gradient portion of the curved gradient you have to take a narrow slice of the gradient from the focus point outward that represents the colors involved.

In the example I created the top gradient from PS then curved the gradient. Then I started over with a clean image. I duplicated the gradient taking samples at each of 8 12.5% points along the path (drawn). That gave me the gradient. Then I used the shear filter to make the curve. The bottom image is the recreated duplicate.

Here's how to divide an image evenly. First make sure snap is on.

1. Use the retangle marquee to make a selection around the entire image or even a retangular portion of the image that runs from the top to bottom extremes of the gradient you are trying to reproduce.

2. Then move a guide line to the mid point of the selection. Guess what! PS automatically finds the center point of the selection and will snap the guide to there.

3. Then make a new selection with the marquee tool from that guide to the top and repeat from the guide to the bottom. Each time move a guide to the center point (snap) of that selection.

By doing this over and over you can accurately divide the picture into portions that you can find on the location slider of the gradient editor.

Now that you have the gradient that duplicates the sky or whatever you can replace the bad background with the good background.

By the way, this method works with luminescence masks, or any other kind of mask. Let's say you want to reproduce the gradual gradiated darkening of a wallboard behind someone that needs retouching. Simply reproduce the texture of the wallboard then add the gradual change in color or shadow change by first extracting a representitive gradient of the luminence and then reproduce it with a gradient mask using the above method.

Hope this helps.

Tex
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  #15  
Old 01-14-2003, 10:54 AM
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jeaniesa jeaniesa is offline
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Wow - what a great description Tex!! THANKS!!

Jeanie
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  #16  
Old 01-14-2003, 01:02 PM
kthurner kthurner is offline
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Thanks for your detailed procedure Tex. This will be a useful technique for me in the future I'm sure. However, your earlier comment is true, the sky in this image is too complex for me to be able to match the undulations in gradient that occur. Perhaps I simply haven't mastered it.

As an addendum to my previous post of the procedure I'm using, adding a small Radial Zoom Blur completely wipes out any signs of pixelization from the resampling steps. I am now quite happy with the results.

And yes Jeanie, the image file is a drum scan of a 35mm transparency.

Thanks again for all your input.

Last edited by kthurner; 01-14-2003 at 09:09 PM.
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