Polarizer Problem

SU
Posted By
Stefan Ulrich Fischer
May 26, 2006
Views
367
Replies
7
Status
Closed
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.

Stefan Ulrich Fischer

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N
noone
May 26, 2006
In article , stefan.
says…
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.
Stefan Ulrich Fischer

Stefan,

What you are seeing is vignetting at the lens outer edge. If your sensor was circular, and the resulting image was circular, you would see a dark circle ( soft edged) around the entire image.

If you shoot in RAW format, and Adobe Camera Raw plug-in supports your camera, you can minimize this vignetting in the settings – second tab, and under " Vignetting" IIRC.

If you have not shot RAW, then the best thing to do is create a Radial Gradient Layer Mask. This will be a bit of trial-n-error, to get the radius and the degree of transparency to black correct, but once you have created it, you can Save this Alpha Channel for use on other images done with the Polarizer. Open one of the images with noticible vignetting. Hit Q (for Quick Mask Mode), Open the Gradient Tool, and set the Options box to Radial, then Black to Transparent. Experiment with dragging the Gradient Tool from a corner to the center of the image, moving your mid-point on the Gradient Tool to try and match the vignetting. Once you have gotten it very close, hit Q again and you will have an active Selection, which you will Save (Selection). Now you can use that Selection for an Adjustment Layer. I’d start with Levels, or Curves, knowing that an Adjustment Layer for Color Balance, and/or Hue/ Brightness/Saturation might also be needed. Explore the Adjustment Layer settings to match the edges of your image to the center.

Another way would be to hit Q, create a circle (Ellipse Tool, Alt/Shift to draw from center/constrain circle), then Fill, Ctrl-Alt-I to Invert), then experiment with Gaussian Blur on the edges of the circle. I think Gradient Tool is a better starting point, but that’s just me.

You might want to look into a larger Polarizer and necessary step-up ring, but are likely to still get some vignetting just from the Polarizing effect.

Hunt
K
KatWoman
May 26, 2006
"Stefan Ulrich Fischer" wrote in message
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.
Stefan Ulrich Fischer

is the darker part from the scan? or you messed up taking the shot?? try removing the sunshade from your camera when using the flash? crop the image?
or try and fix as described by Mike
K
KatWoman
May 26, 2006
"Stefan Ulrich Fischer" wrote in message
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.
Stefan Ulrich Fischer

err I meant Hunt
SU
Stefan Ulrich Fischer
May 26, 2006
KatWoman wrote:
"Stefan Ulrich Fischer" wrote in message
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.
Stefan Ulrich Fischer

err I meant Hunt

No, I used my 35mm camera (Minolta XD-7 or Canon EOS Rebel GII) and the polarizer on my Soligor. One image looks like this:

http://newton-i.usefilm.com/images/4/3/1/5/4315/1104669-larg e.jpg

I hope it works without logging in. It just bothered me, cause I didn’t see the result before I got the image printed on paper. Thanks for the answers.

Stefan Ulrich
K
Kingdom
May 26, 2006
"Stefan Ulrich Fischer" wrote in
news::

http://newton-i.usefilm.com/images/4/3/1/5/4315/1104669-larg e.jpg

In photoshop
Try using shadow/highlight and or lightly brushing with the Doge tool, try setting the exposere (on the options bar) at about 20% – 30%
K
KatWoman
May 26, 2006
"Stefan Ulrich Fischer" wrote in message
KatWoman wrote:
"Stefan Ulrich Fischer" wrote in message
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.
Stefan Ulrich Fischer

err I meant Hunt

No, I used my 35mm camera (Minolta XD-7 or Canon EOS Rebel GII) and the polarizer on my Soligor. One image looks like this:

http://newton-i.usefilm.com/images/4/3/1/5/4315/1104669-larg e.jpg
I hope it works without logging in. It just bothered me, cause I didn’t see the result before I got the image printed on paper. Thanks for the answers.

Stefan Ulrich

just quickly
make another level layer, with sky correct at the right (facing us)(quick guess by eye 0,1.51,215)
made a gradient mask to affect only the right side
left side stays same as it was
nice blend using gradients (make sure colors are on default b/w) use the transparent to black across from left to right
http://s15.quicksharing.com/v/6224326/1corrected.jpg.html
N
noone
May 27, 2006
In article , stefan.
says…
KatWoman wrote:
"Stefan Ulrich Fischer" wrote in message
Hello,

if I scan my photos or slides, I have sometimes dark blue corners or parts in the image from the polarizer. Some looks like getting black. It looks especially in the blue sky weird. How can I remove this without getting edges or noise in the blue sky? I use Photoshop CS 8.0.
Stefan Ulrich Fischer

err I meant Hunt

No, I used my 35mm camera (Minolta XD-7 or Canon EOS Rebel GII) and the polarizer on my Soligor. One image looks like this:

http://newton-i.usefilm.com/images/4/3/1/5/4315/1104669-larg e.jpg
I hope it works without logging in. It just bothered me, cause I didn’t see the result before I got the image printed on paper. Thanks for the answers.

Stefan Ulrich

Stefan,

What you are experiencing is not true vignetting, but a difference in the Polarizing effect across the frame, due to the angle of the light source. It is usually more pronounced in WA shots, as, basically, part of your image (sky in your case) actually sees more Polarization, than does the other. Instead of my suggest on using a Radial Gradient, you will want to use a Linear Gradient to try and equalize the amount of Polarization. By doing a Linear Gradient Layer Mask, and toning DOWN the darkening on the right, then Inverting the Mask and darkening on the left, you can get much closer. I’d look into using a Curves Adjustment Layer. You might want to remove the foreground and middle -ground areas from your Adjustment Layer Mask so you are dealing with mostly the sky.

Sorry for my mistake and thanks for posting the link – it worked fine. Also, sorry if I’m typing gibberish, as the sun is in my eyes right now.

Hunt

Master Retouching Hair

Learn how to rescue details, remove flyaways, add volume, and enhance the definition of hair in any photo. We break down every tool and technique in Photoshop to get picture-perfect hair, every time.

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