Daviskw
March 5th, 2006, 10:48 PM
I have a terrible time color correcting and decided to figure a way to at least be consistent from photo to photo in my workflow. The procedures I use below will not instantly and uniformly color correct every photo but it will provide a neutral base that color can be added or subtracted without introducing more color shifts.
This procedure is long and can be a little complicated but I believe it needs to be this way for consistency. It can be done the same way every time with consistent results…which is the goal!! I use it where I am having problems using standard procedures.
Correction is an art that by its very nature cannot be consistent. For instance, if you take a picture in the early morning and at 12 noon of the exact same subject each will be very different in color but both will have correct and appropriate tones.
My goal was to take any picture and balance the white, black, and neutral or gray points. Then be able, if necessary, to apply color in a consistent manner to complete correction.
Here is my workflow then I will supply details;
1.) LOOK at picture!!!!!…NO really LOOK at picture; see if you can identify the color problems before you start.
2.) Open the info box from the windows menu we will use it to track changes in the photo as we color correct.
3.) Identify representative areas in your photo that should be white, black and a neutral color such as gray. Mark those areas on separate layers so they can be returned to accurately.
4.) Using a levels adjustment layer, alter and track the white, black, gray markers until they read as neutral.
5.) Final color correcting by adding or subtracting.
6.) Brightness and contrast final adjustments.
Ways to find black and white points;
The White point on the Levels histogram we want, does not necessarily represent the whitest point on the picture. We want it to represent the whitest point where there is no longer detail in the white color. Otherwise you would not want to color correct the white in the whole picture based on an over bright sun reflection off a car bumper. However we may use the white in the whitewall tire. Same with black, find an area that just no longer has detail.
1.) The white and black points may be obvious like a white shirt or piece of paper, a black shirt or deeply shaded area. If not we can find it in at least two ways.
a. Option#1 Open a Levels adjustment layer. Hold the Alt key, then click the rightmost white triangle slider handle under the histogram and slowly move to the left. When colors start to appear they represent the brightest of that color being pure or clipped, this is our white point. When you see an area that you will be able to locate again in the photo release the Alt key. You can toggle the Alt on or off until you are sure you can locate the area. To find the black point hold the Alt key and slide the black or triangle to the left and move to the right. When you start to see black that is your black point, remember it. Close the levels box and make a color marker as described in the next white /black point example (b).
b. Option #2 Open a Threshold adjustment layer at the top of the pallet. Slide the adjustment triangle all the way to the right. Slowly slide to the left until you see white. Click ok, the black and white image will remain until we delete the Threshold layer. Click on your background picture layer and choose the Elliptical Marquee tool. Find the best area of white on your picture. Click in the center then start to drag, now press the Alt and Shift key and the circle will draw from the click point. Keep the circle very small you want to be able to click in the center so you can go to the same point more than once. Now press Ctrl J to put the circle on its own layer. Name the layer Whites. Now stroke the circle with 1 point red color by Edit>Stroke Selection …go with defaults, change color as necessary. We have made a color marker. Click back on your background. To find the black point reopen the threshold box and slide the triangle all the way to the left then move to the right until black appears. Click back on the background and make a color marker as above. Drag the Threshold layer to the trash can we are done with it.
http://img483.imageshack.us/img483/3928/bw17yl.th.jpg (http://img483.imageshack.us/my.php?image=bw17yl.jpg)
We now have three layers one each of small circles representing white and black, and the background layer.
Finding the Gray or mid point.
If there is an obvious gray in your picture make a color marker on its own layer as with the white/black markers (b). Sometimes a shadow on a white building or a color that you know represents an average brightness or neutral color. If you are not sure, below is a way to find the gray point on most photos.
1.) Duplicate your background layer.
2.) On your duplicate layer press Edit>Fill Layer… in the contents box choose 50% gray, normal 100 percent the click OK.
3.) Change the layer blendmode to Difference. Located on the layer pallet option menu in the drop box labeled Normal
4.) Now open a Threshold Adjustment layer at the top of the pallet. Slide the adjustment all the way to the left. Slowly slide to the right until black appears… this is the gray point. Click ok on the threshold layer then click on your background layer and make a color maker as in (b) above ..label the layer mid or gray. You can now drag the threshold, and the duplicate layer to the trash. You should now have three marker layers and the background layer.
http://img483.imageshack.us/img483/9592/graypoint7vj.th.jpg (http://img483.imageshack.us/my.php?image=graypoint7vj.jpg)
Now we are ready to correct. Be sure you have your Info box open … Windows>Info
Click on your background layer and zoom in to the white color marker. Click the eyedropper tool and center it in the color maker circle. Look at the readings in the Info pallet. You will see readings for R-Red…G-green… B-Blue. If you see two rows of numbers the row on the right is the most recent.
When setting the white point we always want to match the HIGHEST reading. Say R=254 G=241 and B=240. We will increase the Green and Blue to equal the red as follows;
1.) On a Levels adjustment layer at the top of the pallet.
2.) In the channel drop box choose green channel
3.) Select or highlight the “ 255” in the Input levels box.
4.) Now center you dropper in the white color marker and watch the info box. Press the down arrow key on the keyboard and watch the green numbers increase. You may need to slightly move or giggle the eyedropper to update the info box. Keep clicking until the green numbers match the highest number… the red in my case, could be a different color in your picture.
5.) Do the same with the blue. When all three numbers are the same or within a point or two you have successfully neutralized the white colors in your photo… on to the gray point next.
Now click OK to close the levels box. Zoom to the gray or mid color marker. Move the eyedropper to the center of the gray color marker. Note the reading. For the gray point add all three values together then divide by three for an average reading. This reading will be the target values for all three channels. In this case R=150…G=172 B=192 for an average of 171.
1.) Open the Levels box again.
2.) Choose the Red channel
3.) Select the 1.0 in the Input Levels box
4.) Click the down or the up arrows as need until the value reaches your average.
5.) Do the same with the other two channels. Often an error here is to not highlight the 1.0 value for each channel. When all three values are at or near your target average you have neutralized the gray or mid point. Now for black.
http://img407.imageshack.us/img407/6057/correcting5ci.th.jpg (http://img407.imageshack.us/my.php?image=correcting5ci.jpg)
As above temporarily close the levels box and zoom to the black color marker. Move the eyedropper to the center and note the values. With black point we will match the LOWEST values. In my example Green is the lowest and I will adjust the red and blue to match as follows;
1.) Open the levels box again
2.) Choose the red channel
3.) Select the 0 in the input levels box.
4.) Click the up arrow key until the values matches your lowest value.
5.) Do the same with the other channel until all values are close to the same.
Now the photo white…black…and mid gray points are neutralized. Your colors may be good enough now and all you need to do is adjust the gamma in the RGB channel for brightness, the center gray triangle when the channel is RGB. You may need to increase contrast by slightly moving the white triangle and the black triangle a little closer together.
If the colors still do not look right…. NOW we will fix that by adding or subtracting colors.
Remember this very Important.
To adjust Red..In the Red channel, move the slider to the left to add, to the right to subtract
To adjust Blue..In the Blue channel, move the slider to the left to add, to the right to subtract.
To adjust Green..In the Green channel, move the slider to the left to add, the right to subtract.
To adjust Yellow..In the Blue channel, reduce blue to add yellow, Increase blue to remove yellow
To adjust Magenta..In the Green channel reduce green to add magenta, Increase green to remove magenta
To adjust Cyan..In the Red channel reduce red to add cyan, Increase red to remove cyan
Adjust one color at a time adding and subtracting as needed. When done with the colors adjust brightness and contrast as needed.
Drag the color marker layers to the trashcan to remove the color circles from your photo.
This tutorial does not take into consideration photos with multiple color problems but you can use these methods in conjunction with gradients and brushes in the layer masks.
Butch
This procedure is long and can be a little complicated but I believe it needs to be this way for consistency. It can be done the same way every time with consistent results…which is the goal!! I use it where I am having problems using standard procedures.
Correction is an art that by its very nature cannot be consistent. For instance, if you take a picture in the early morning and at 12 noon of the exact same subject each will be very different in color but both will have correct and appropriate tones.
My goal was to take any picture and balance the white, black, and neutral or gray points. Then be able, if necessary, to apply color in a consistent manner to complete correction.
Here is my workflow then I will supply details;
1.) LOOK at picture!!!!!…NO really LOOK at picture; see if you can identify the color problems before you start.
2.) Open the info box from the windows menu we will use it to track changes in the photo as we color correct.
3.) Identify representative areas in your photo that should be white, black and a neutral color such as gray. Mark those areas on separate layers so they can be returned to accurately.
4.) Using a levels adjustment layer, alter and track the white, black, gray markers until they read as neutral.
5.) Final color correcting by adding or subtracting.
6.) Brightness and contrast final adjustments.
Ways to find black and white points;
The White point on the Levels histogram we want, does not necessarily represent the whitest point on the picture. We want it to represent the whitest point where there is no longer detail in the white color. Otherwise you would not want to color correct the white in the whole picture based on an over bright sun reflection off a car bumper. However we may use the white in the whitewall tire. Same with black, find an area that just no longer has detail.
1.) The white and black points may be obvious like a white shirt or piece of paper, a black shirt or deeply shaded area. If not we can find it in at least two ways.
a. Option#1 Open a Levels adjustment layer. Hold the Alt key, then click the rightmost white triangle slider handle under the histogram and slowly move to the left. When colors start to appear they represent the brightest of that color being pure or clipped, this is our white point. When you see an area that you will be able to locate again in the photo release the Alt key. You can toggle the Alt on or off until you are sure you can locate the area. To find the black point hold the Alt key and slide the black or triangle to the left and move to the right. When you start to see black that is your black point, remember it. Close the levels box and make a color marker as described in the next white /black point example (b).
b. Option #2 Open a Threshold adjustment layer at the top of the pallet. Slide the adjustment triangle all the way to the right. Slowly slide to the left until you see white. Click ok, the black and white image will remain until we delete the Threshold layer. Click on your background picture layer and choose the Elliptical Marquee tool. Find the best area of white on your picture. Click in the center then start to drag, now press the Alt and Shift key and the circle will draw from the click point. Keep the circle very small you want to be able to click in the center so you can go to the same point more than once. Now press Ctrl J to put the circle on its own layer. Name the layer Whites. Now stroke the circle with 1 point red color by Edit>Stroke Selection …go with defaults, change color as necessary. We have made a color marker. Click back on your background. To find the black point reopen the threshold box and slide the triangle all the way to the left then move to the right until black appears. Click back on the background and make a color marker as above. Drag the Threshold layer to the trash can we are done with it.
http://img483.imageshack.us/img483/3928/bw17yl.th.jpg (http://img483.imageshack.us/my.php?image=bw17yl.jpg)
We now have three layers one each of small circles representing white and black, and the background layer.
Finding the Gray or mid point.
If there is an obvious gray in your picture make a color marker on its own layer as with the white/black markers (b). Sometimes a shadow on a white building or a color that you know represents an average brightness or neutral color. If you are not sure, below is a way to find the gray point on most photos.
1.) Duplicate your background layer.
2.) On your duplicate layer press Edit>Fill Layer… in the contents box choose 50% gray, normal 100 percent the click OK.
3.) Change the layer blendmode to Difference. Located on the layer pallet option menu in the drop box labeled Normal
4.) Now open a Threshold Adjustment layer at the top of the pallet. Slide the adjustment all the way to the left. Slowly slide to the right until black appears… this is the gray point. Click ok on the threshold layer then click on your background layer and make a color maker as in (b) above ..label the layer mid or gray. You can now drag the threshold, and the duplicate layer to the trash. You should now have three marker layers and the background layer.
http://img483.imageshack.us/img483/9592/graypoint7vj.th.jpg (http://img483.imageshack.us/my.php?image=graypoint7vj.jpg)
Now we are ready to correct. Be sure you have your Info box open … Windows>Info
Click on your background layer and zoom in to the white color marker. Click the eyedropper tool and center it in the color maker circle. Look at the readings in the Info pallet. You will see readings for R-Red…G-green… B-Blue. If you see two rows of numbers the row on the right is the most recent.
When setting the white point we always want to match the HIGHEST reading. Say R=254 G=241 and B=240. We will increase the Green and Blue to equal the red as follows;
1.) On a Levels adjustment layer at the top of the pallet.
2.) In the channel drop box choose green channel
3.) Select or highlight the “ 255” in the Input levels box.
4.) Now center you dropper in the white color marker and watch the info box. Press the down arrow key on the keyboard and watch the green numbers increase. You may need to slightly move or giggle the eyedropper to update the info box. Keep clicking until the green numbers match the highest number… the red in my case, could be a different color in your picture.
5.) Do the same with the blue. When all three numbers are the same or within a point or two you have successfully neutralized the white colors in your photo… on to the gray point next.
Now click OK to close the levels box. Zoom to the gray or mid color marker. Move the eyedropper to the center of the gray color marker. Note the reading. For the gray point add all three values together then divide by three for an average reading. This reading will be the target values for all three channels. In this case R=150…G=172 B=192 for an average of 171.
1.) Open the Levels box again.
2.) Choose the Red channel
3.) Select the 1.0 in the Input Levels box
4.) Click the down or the up arrows as need until the value reaches your average.
5.) Do the same with the other two channels. Often an error here is to not highlight the 1.0 value for each channel. When all three values are at or near your target average you have neutralized the gray or mid point. Now for black.
http://img407.imageshack.us/img407/6057/correcting5ci.th.jpg (http://img407.imageshack.us/my.php?image=correcting5ci.jpg)
As above temporarily close the levels box and zoom to the black color marker. Move the eyedropper to the center and note the values. With black point we will match the LOWEST values. In my example Green is the lowest and I will adjust the red and blue to match as follows;
1.) Open the levels box again
2.) Choose the red channel
3.) Select the 0 in the input levels box.
4.) Click the up arrow key until the values matches your lowest value.
5.) Do the same with the other channel until all values are close to the same.
Now the photo white…black…and mid gray points are neutralized. Your colors may be good enough now and all you need to do is adjust the gamma in the RGB channel for brightness, the center gray triangle when the channel is RGB. You may need to increase contrast by slightly moving the white triangle and the black triangle a little closer together.
If the colors still do not look right…. NOW we will fix that by adding or subtracting colors.
Remember this very Important.
To adjust Red..In the Red channel, move the slider to the left to add, to the right to subtract
To adjust Blue..In the Blue channel, move the slider to the left to add, to the right to subtract.
To adjust Green..In the Green channel, move the slider to the left to add, the right to subtract.
To adjust Yellow..In the Blue channel, reduce blue to add yellow, Increase blue to remove yellow
To adjust Magenta..In the Green channel reduce green to add magenta, Increase green to remove magenta
To adjust Cyan..In the Red channel reduce red to add cyan, Increase red to remove cyan
Adjust one color at a time adding and subtracting as needed. When done with the colors adjust brightness and contrast as needed.
Drag the color marker layers to the trashcan to remove the color circles from your photo.
This tutorial does not take into consideration photos with multiple color problems but you can use these methods in conjunction with gradients and brushes in the layer masks.
Butch