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Odd problem with add to and subtract from selection tools. Help please!


skrode_rider

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I'm having a really frustrating problem with adding to and subtracting from selections. I've tried to find a solution to the problem online, but can't seem to find any mention of anybody else also experiencing it, which makes me think it's either something really simple and stupid I'm doing wrong, or something very strange. It's kind of complicated to describe, but I'll try.

I use ps primarily to tweek my photos to make them look nicer. Let's say I'm trying to make the sky darker. I create a new layer with the image in it, Then I'll go to select color range and work with that to try and get as much of the sky and as little of everything else in the selection. Of course it isn't perfect, so I'll go in try to subtract and add areas to the selection. Let's say there's a little piece of the sky that for whatever reason didn't make it into the selection. I'll go to either the rectangular marquee or the lasso, and then add that area to the selection by holding shift. The area is then added to the selection, and everything looks like it's going fine, right?

When I apply the desired change to the selection, usually by adjusting the curves or adding a mask and changing the blending options, something terrible happens. The whole selected sky areas turns darker, but the areas that I added to the selection become even darker. So there will be a little extra darker shape exactly where I added to the selection. If I used the rectangular marquee, the darker area will be a little rectangle, if I used the lasso the darker shape will be exactly what ever shape I drew around the pixels I added to the selection.

This same thing happens when I use subtract from the selection. I've tried inverting the selection and subtracting then inverting again and all sorts of other things but nothing works, I keep getting these weird shadows wherever I added or subtracted. It's totally bizarre.

I'm using cs6 on windows 10. I've tried deleting my preferences and all sorts of other things, but nothing works and I'm getting incredibly frustrated. I've even had this problem on my other computer, which is running cs6 windows 8.

Please, please, can anybody have any idea what's going on here? I'm desperate.
 

MrToM

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Don't get frustrated.

Can you post a screen shot of the WHOLE UI including the image WITH the problem?

Seeing it will make it much easier to understand the problem and come to a solution.

Regards.
MrToM.
 

skrode_rider

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Okay. I hope this will help you help me.

Here is an image I may want to tweek the sky on. I've duplicated the background into a new layer.
1.jpg


In this next screenshot, I've used select>color range to select much of the sky. Note the areas of the sky not in the selection.
2.jpg


In the next screenshot, I have used the rectangular marquee selection tool, and "add to selection," drawing boxes around the areas that werent in the original selection. Looks like I have the just the sky selected, right?
3.jpg


In this next screenshot, I have added a layer mask, and then changed the blending from "normal" to "multiply" to darken the sky. If I had instead adjusted the curves, the result would be the same. The problem is most clearly visible on the far right side of the sky. You can see the rectangular shape that became even darker than the rest of the sky. That rectangular shape is exactly the shape of the area I added to the selection in the previous step.
4.jpg


What is going on???
 

MrToM

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OK....I'm basing this off the microscopic thumbnail of the layer mask but check it out.....it doesn't look to be completely 100% white where the sky is nor 100% black where the rest of it is...

mask_problem_MT_01.png

Its only a guess but....?

Sometimes an area can 'look' white when in fact it isn't quite.....and when using blending modes even a difference of 1 in an RGB value can show up like a baboons bum.

Just check if all the pixels are as they should be.

Regards.
MrToM.
 

MrToM

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As it stands?

Create the marquee again.....then either just paint it white with the brush or fill it with white with the paint bucket....same for the black...use SELECT > INVERSE and it'll swap the marquee (the ground will have the marquee around it)....then paint in black....or fill.

If you use the paint bucket click it a few times......you may have some 'odd' pixels around the edge and one click isn't enough to fill them.....I usually use the paint brush just to be sure.

Was that the problem BTW?

It was just a guess as the thumbnail wouldn't have any other colour in it if it was perfect......smaller images are sometimes more useful than larger ones as being re-sampled they show up the blemishes.

Regards.
MrToM.
 

IamSam

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Thanks, Mr. Tom. Fascinating. Quick question: how do I make sure the pixels are all white?
I know you asked MrToM..............but I would use a different selection process for selecting the sky.
Here I have used an alpha channel to get a perfect black and white selection I can use for the mask.

Screen Shot 2015-09-17 at 11.05.21 PM.png

Screen Shot 2015-09-17 at 11.08.12 PM.png
 

skrode_rider

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Thanks IamSam, I'd try that too, if I had any idea how....

Mr. tom, that did the trick! Thank you so much. I guess it turns out the problem area wasn't turning darker after all. Rather, the pixels all around it were just a little lighter.

Seems like despite how long I've been using photoshop, and how good I think I am with it, I'm really just a know-little-noob. There is just soooo much to it.

Thanks again!!!
 

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