Hello
I am posting two jpg files that were corrected in CM; one using Lab and the other RGB. I believe the RGB version came out better.
In a message about color wizard trouble you state that using the color wizard with Lab leads to bad results so I used the menu option to set the shadow, highlight and neutral point. I did, however, use the color wizard for the RGB version. Again, I like the RGB version of the correction better than the Lab version.
What do you think?
Thank you
David
Cm Week 1 Ducks Assignment
David,
RGB First...from your posted image...
Very nice image...You found a solid neutral and have a well balanced image. Shot1 shows some VERY minor changes for your consideration. These are by no means required but...They do make the image look brighter and cleaner.
Notice that I added the Master channel to the CM tool by going into the configuration area and adding the master channel to the display.
From the RGB master channel I increased the contrast by moving the ends of the Master curve just a tiny bit closer to the center of the grid. Once I did that the white patch on the wing looked "off" the Hue clock shows that it is not a neutral white. I adjusted the Blue curve just a tiny bit to clean that up.
Greg
RGB First...from your posted image...
Very nice image...You found a solid neutral and have a well balanced image. Shot1 shows some VERY minor changes for your consideration. These are by no means required but...They do make the image look brighter and cleaner.
Notice that I added the Master channel to the CM tool by going into the configuration area and adding the master channel to the display.
From the RGB master channel I increased the contrast by moving the ends of the Master curve just a tiny bit closer to the center of the grid. Once I did that the white patch on the wing looked "off" the Hue clock shows that it is not a neutral white. I adjusted the Blue curve just a tiny bit to clean that up.
Greg
- Attachments
-
- shot1-jpg-16 (293.3 KiB) Viewed 11815 times
And Now...LAB...From your posted image...
One of the problems with LAB at first is that it tends to de-saturate images during the initial correction. Thankfully CM provides a tool in LAB to fix that. The Saturation Slider is found in the lower Right of the screen shot. The number next to the end of the slider is more for comparison rather than target values.
I also worked on the L curve just a bit to make this image open up a bit. Try setting hue clocks as shown and making small adjustments to the A and B channels to get the leg band to be neutral. Then adjust the saturation slider to make the colors pop out...Lastly you can adjust the L channel to open the shadows and reduce the highlights slightly.
This is tough image to work with in LAB without the Wizard as a first go out of the chute...have patience with the LAB space and hopfully you will come to like the results better as you get more practice in there.
Greg
One of the problems with LAB at first is that it tends to de-saturate images during the initial correction. Thankfully CM provides a tool in LAB to fix that. The Saturation Slider is found in the lower Right of the screen shot. The number next to the end of the slider is more for comparison rather than target values.
I also worked on the L curve just a bit to make this image open up a bit. Try setting hue clocks as shown and making small adjustments to the A and B channels to get the leg band to be neutral. Then adjust the saturation slider to make the colors pop out...Lastly you can adjust the L channel to open the shadows and reduce the highlights slightly.
This is tough image to work with in LAB without the Wizard as a first go out of the chute...have patience with the LAB space and hopfully you will come to like the results better as you get more practice in there.
Greg
- Attachments
-
- shot2-jpg-8 (295.85 KiB) Viewed 11815 times
Hello.
This pertains to the Duck image in Lab.
I did not notice the Saturation Slider under the Lab curves and it definitely makes a big difference. I also, thought the Lab image looked desaturated but was not sure what to do.
Also, I have a question about the Hue Clocks. When the cursor touches a point in the image, the Hue Clock by the Curves Window changes, however, I cannot get the Hue Clock Windows to display on the actual image. How did you get them to display on your image of the screen you posted?
You showed Hue Clocks for five points. Please explain, how you work with more than three points; I thought you could only have one Shadow, Highlight and Neutral point. I might be jumping ahead by asking this question, especially since I am stilling working on week 1 Ducks, but I am still curious.
As you can see the image looks a lot better. Please give me your advice on this image.
Thank you
David
This pertains to the Duck image in Lab.
I did not notice the Saturation Slider under the Lab curves and it definitely makes a big difference. I also, thought the Lab image looked desaturated but was not sure what to do.
Also, I have a question about the Hue Clocks. When the cursor touches a point in the image, the Hue Clock by the Curves Window changes, however, I cannot get the Hue Clock Windows to display on the actual image. How did you get them to display on your image of the screen you posted?
You showed Hue Clocks for five points. Please explain, how you work with more than three points; I thought you could only have one Shadow, Highlight and Neutral point. I might be jumping ahead by asking this question, especially since I am stilling working on week 1 Ducks, but I am still curious.
As you can see the image looks a lot better. Please give me your advice on this image.
Thank you
David
- Attachments
-
- 20101215_duck_cm_lab_redo1-jpg (166.62 KiB) Viewed 11815 times
-
sjordan93436
- Posts: 462
- Joined: Sun Jul 11, 2010 4:23 am
- Contact:
Steve is correct. To take it further and give you even more to work with....
In Photoshop you can set sample points when you work with curves. You are only able to see the numbers for the sample points and you have to remember what point measures what. In Curvemeister I can set as many sample points as I want by Alt-Clicking on the image. This allows me to measure more than three points. I need not limit myself to only three. I can have a dozen or more...I need only have enough to make wise decisions about the color in the image. Do I make adjustments based on all of them?? No.Not at all....I look for obvious problems...Green Hair, Pink clouds, Blue Fur....Hue clocks give me information I use to adjust these problems out of my images.
If you notice on the duck I set hue clocks on a shadow, A highlight and a mid tone. Then I added hue clocks to areas of the bird I wanted to verify the colors in...My adjustment to the blue was based on the highlight value on the wing. I wanted the white feathers to be neutral...the numbers tell me it is not...If it was all three numbers would be the same...like your neutral setting on the gray leg band. I can give up 1 or 2 points on the specific point because of the sample size...In CM when you set a hue clock you are not sampling an exact point you are getting a Sample based on the size in your configuration settings. My Sample size is 3X3. That means I am looking at the average of 9 Pixels.
Another example... In RGB it is possible to have a color cast based on the brightness of the image. It is one of the strengths of RGB to be able to adjust the color in the shadows differently than the color in the highlights or even the mid-tones. I can have multiple neutrals based on brightness. Later in the class we use this to do a "Color By the Numbers" correction. This industry standard correction can be difficult in Photoshop because you can set sample points; but you have no visual reference for the actual color or sample point. Hue clocks solve that problem.
You did a great job with the image after adding saturation in LAB. Hue clocks help in LAB as well but the adjustments are different. In LAB the color starts in the center of the channel. It is the only place that is neutral. You split the colors by channel as you have seen and you need to add more control points to the curve line to hold it in place while you adjust....I'll look at the image in greater detail in the next posting...
Greg
In Photoshop you can set sample points when you work with curves. You are only able to see the numbers for the sample points and you have to remember what point measures what. In Curvemeister I can set as many sample points as I want by Alt-Clicking on the image. This allows me to measure more than three points. I need not limit myself to only three. I can have a dozen or more...I need only have enough to make wise decisions about the color in the image. Do I make adjustments based on all of them?? No.Not at all....I look for obvious problems...Green Hair, Pink clouds, Blue Fur....Hue clocks give me information I use to adjust these problems out of my images.
If you notice on the duck I set hue clocks on a shadow, A highlight and a mid tone. Then I added hue clocks to areas of the bird I wanted to verify the colors in...My adjustment to the blue was based on the highlight value on the wing. I wanted the white feathers to be neutral...the numbers tell me it is not...If it was all three numbers would be the same...like your neutral setting on the gray leg band. I can give up 1 or 2 points on the specific point because of the sample size...In CM when you set a hue clock you are not sampling an exact point you are getting a Sample based on the size in your configuration settings. My Sample size is 3X3. That means I am looking at the average of 9 Pixels.
Another example... In RGB it is possible to have a color cast based on the brightness of the image. It is one of the strengths of RGB to be able to adjust the color in the shadows differently than the color in the highlights or even the mid-tones. I can have multiple neutrals based on brightness. Later in the class we use this to do a "Color By the Numbers" correction. This industry standard correction can be difficult in Photoshop because you can set sample points; but you have no visual reference for the actual color or sample point. Hue clocks solve that problem.
You did a great job with the image after adding saturation in LAB. Hue clocks help in LAB as well but the adjustments are different. In LAB the color starts in the center of the channel. It is the only place that is neutral. You split the colors by channel as you have seen and you need to add more control points to the curve line to hold it in place while you adjust....I'll look at the image in greater detail in the next posting...
Greg
The Image seems to have a couple of things going on....See shot1.
Setting a better neutral will help the leg band not look so blue. But when you do set a neutral the image turns green...It is the biggest problem with LAB...You have to bet on the neutral. If you miss you end up fighting the color cast. Use the hue clock on the upper right of the CM interface to find a place on the leg band where the A and B channels are equal and +/- 1 of zero....
In Shot 2 you can see how I adjusted the A and B curves to get the color back in balance...I did not set a neutral because I did not want to fight the green cast the legband adds based on your initial correction.
I also saved the ACV file for you to load...Take you image as posted and load the ACV file from the desktop using CM. Take a look at the B channel and move the points closest to the center around slowly. You should get a feel for the correction....
Great stuff...
Greg
Setting a better neutral will help the leg band not look so blue. But when you do set a neutral the image turns green...It is the biggest problem with LAB...You have to bet on the neutral. If you miss you end up fighting the color cast. Use the hue clock on the upper right of the CM interface to find a place on the leg band where the A and B channels are equal and +/- 1 of zero....
In Shot 2 you can see how I adjusted the A and B curves to get the color back in balance...I did not set a neutral because I did not want to fight the green cast the legband adds based on your initial correction.
I also saved the ACV file for you to load...Take you image as posted and load the ACV file from the desktop using CM. Take a look at the B channel and move the points closest to the center around slowly. You should get a feel for the correction....
Great stuff...
Greg
- Attachments
-
- screenshot001-jpg-29 (93.77 KiB) Viewed 11815 times
-
- screenshot002-jpg-24 (164.35 KiB) Viewed 11815 times
-
- 20101215_duck_cm_lab_redo1-labgg-acv
- (82 Bytes) Downloaded 577 times
Hello.
Thank you for your quick response. By the way, the videos on Hue Clocks and Thresholds were very helpful. So far, I have learned much from this class and it has just started. I am still relatively new to curves.
With respect to Lab, why does working with Lab often lead to desaturation? Also, why does setting a neutral often cause color cast? As a general rule, would you recommend avoiding a neutral when using Lab or correcting the color cast. In general, how do you correct a color cast in Lab? Also, please summarize all the benefits of Lab vs RGB?
Thank you
David
Thank you for your quick response. By the way, the videos on Hue Clocks and Thresholds were very helpful. So far, I have learned much from this class and it has just started. I am still relatively new to curves.
With respect to Lab, why does working with Lab often lead to desaturation? Also, why does setting a neutral often cause color cast? As a general rule, would you recommend avoiding a neutral when using Lab or correcting the color cast. In general, how do you correct a color cast in Lab? Also, please summarize all the benefits of Lab vs RGB?
Thank you
David
David,
Lab is a bit more difficult to color correct in than RGB. It is not impossible just harder. The primary reason is that "neutral" in LAB is really only found in the center of the A and B curves. You can only have 1 neutral in LAB. Sometimes this makes LAB simple...Other times you will need to color correct in RGB and go to LAB for color saturation.
So...
LAB characteristics:
1) Fast
2) Colorful but coarse; subtle color is hard to come by.
3) Separates color from Brightness; You can adjust brightness and contrast without adding color casts.
4) Perceptual color space; meaning it handles color more like we think about and perceive it.
5) Allows for separation of individual colors easily; We will cover this in weeks 5 and 6.
RGB characteristics:
1) Most popular color space; Native color space for most devices.
2) Multiple neutrals are possible separated by brightness. S/H/Mid tone- neutrals are all possible in the same image.
3) Subtle color correction is easily achieved.
4) Vibrant color can be hard to achieve.
5) Contrast and Brightness linked to color. Can cause color casts when changes are made to brightness.
Corrections in LAB lead to desaturation because as you change the L channel you are not changing the color channels. They (A and B) are supplying the same color information with regards to brightness as the original image. When you take a color and lower or raise the luminance you effect the way we perceive the tone and hue and it takes more color input from the A and B channels to reach the same effect. Lab can also be used to desaturate an image effectively.
I color correct in LAB by moving the ends of the curve first. If you remember that the center of the channel is the only part that is neutral you change the neutral point by moving the curve line off the center. It is usually a small move and I use a hue clock to tell me when the chosen point is 0,0. After that I adjust only 1/2 of the A or B channels to effect only 1 color. We do an exercise later in the class where you have to change the color of a Car by using LAB and HSB curves. This part of the coarse will drive home the effects of LAB color corrections.
Setting a neutral in LAB causes the color to shift because you are choosing a new center point for the channels. If you get the selection wrong you introduce color cast. Again only 1 point in LAB can be neutral. I'll try to figure out a way to better show this....
Greg
Lab is a bit more difficult to color correct in than RGB. It is not impossible just harder. The primary reason is that "neutral" in LAB is really only found in the center of the A and B curves. You can only have 1 neutral in LAB. Sometimes this makes LAB simple...Other times you will need to color correct in RGB and go to LAB for color saturation.
So...
LAB characteristics:
1) Fast
2) Colorful but coarse; subtle color is hard to come by.
3) Separates color from Brightness; You can adjust brightness and contrast without adding color casts.
4) Perceptual color space; meaning it handles color more like we think about and perceive it.
5) Allows for separation of individual colors easily; We will cover this in weeks 5 and 6.
RGB characteristics:
1) Most popular color space; Native color space for most devices.
2) Multiple neutrals are possible separated by brightness. S/H/Mid tone- neutrals are all possible in the same image.
3) Subtle color correction is easily achieved.
4) Vibrant color can be hard to achieve.
5) Contrast and Brightness linked to color. Can cause color casts when changes are made to brightness.
Corrections in LAB lead to desaturation because as you change the L channel you are not changing the color channels. They (A and B) are supplying the same color information with regards to brightness as the original image. When you take a color and lower or raise the luminance you effect the way we perceive the tone and hue and it takes more color input from the A and B channels to reach the same effect. Lab can also be used to desaturate an image effectively.
I color correct in LAB by moving the ends of the curve first. If you remember that the center of the channel is the only part that is neutral you change the neutral point by moving the curve line off the center. It is usually a small move and I use a hue clock to tell me when the chosen point is 0,0. After that I adjust only 1/2 of the A or B channels to effect only 1 color. We do an exercise later in the class where you have to change the color of a Car by using LAB and HSB curves. This part of the coarse will drive home the effects of LAB color corrections.
Setting a neutral in LAB causes the color to shift because you are choosing a new center point for the channels. If you get the selection wrong you introduce color cast. Again only 1 point in LAB can be neutral. I'll try to figure out a way to better show this....
Greg
-
sjordan93436
- Posts: 462
- Joined: Sun Jul 11, 2010 4:23 am
- Contact:
Return to “Curvemeister 101 - December 2010”
Who is online
Users browsing this forum: No registered users and 2 guests