Basic curve questions....

[mikemeister_admin]

Hey there Lee!  Thanks for your explanation regarding curves.  I have done that before with poor results.  I think the best way to show what I mean about not using curves is to post a before and after picture, with the after picture not using curves.  The before picture is how the picture looked when I scanned it.

If anyone reading this post is interested,  feel free to play with it if you want to.  This is what I can do without curves.  I would like to see what can be done to it using curves.  I doubt that using curves will make it better, but I'd like to see what using curves can do with this picture. :)

[ggroess]

Art,
We love a good challenge...
The main part of this image is the skin tones.  one of the features of CM is the ability to pin skin tones to a known set of values that make the skin look better or more real.  In your image the skin is cold.  Too much blue...There is an overall blue cast to the image. I also adjusted the exposure a bit since the flash fall off was very evident I decided let the edges drop off as well so as to not change the snapshot feel of the image... With a gentle approach and the proper curves you can make a very large improvement in the image very quickly.  I spend about 3 minutes with my correction.  My curves are not shown...I'll try to re-create them so you can see what was done to the image.

Greg

sample 02_gg= my correction
shot1 your image with hue clocks displayed to show the color
shot 2 my image with hue clocks displayed.

[ggroess]

Art this is typical response to a question you might have while in the class.  not all of them will be this lengthy but they will hopefully show you what you need to try to do.

OK...Step by step...again this really only takes a few minutes once you have a better understanding of Curves.  This is a very good example of what Curvemeister can do.

Step 1 LAB to correct the overall exposure a bit and get the image into a better position to be adjusted.  This step gives me more room to work within the tonal range and give me a better idea of the overall color cast.

Step 2   LAB to increase the saturation of the colors overall because when you adjust the image tonal range in LAB you can kill off a lot of the color.  I used the saturation slider to bring back some of the color so I could go on to step 3. Apply changes and exit Curvemeister.

Step 3 RGB for color correction.    I needed to be able to adjust the skin tones based on the brightness of the area they are located in. Because color in RGB is linked to brightness I had to go to RGB to fix the skin tones. Apply changes and exit Curvemeister.

Step 4 Back to LAB; after the color has been adjusted I wanted to bring more color back.  LAB is the best place to add color after casts have been reduced because color is not linked to brightness in LAB.  Again using the saturation slider I added some color.  I also found that the shadow on the rail behind him became too green so I pinned the red side of the A channel in LAB and adjusted the green down to a more neutral position.  Apply changes and exit.

Greg

[ggroess]

one last thing that is possible with CM..I added a layer mask for the Blue shirt using a channel from LAB.  this allowed me to increase the saturation on the blue shirt  to make it more lively....

Greg

[mikemeister_admin]

Hi Greg!  I appreciate you taking the time to post your technique.  I am impressed with your results.  Mine look pretty bad compared to yours.

Reading your step by step technique, well, I have no idea what you did or what you are taking about.  Your first step, you say "Lab", so I assume you converted the picture to LAB mode, okay, but then you say you adjusted the "exposure".  What is that?  I have never seen any Exposure adjustment, so where do I find that?  Is that the histogram at the top of the three histograms that says "Lightness"? (I noticed that the line in that box has been moved, so maybe that's what you meant when you said "Exposure"?)

If that is what you meant, then my next question....how do you know where to place the anchor point?  Then, how do you know which direction to move it and how much do you move it?  When I say which direction, I mean, do you move the anchor point at a 90 degree angle to the line?....do you move it straight up?....is it a combination of the two?

See, that is what I've read in other tutorials, they just say to move it.  They don't tell you where you need to place the anchor point or how much to move it, they just say grab the line and move it.  I guess you have to just guess at those things right?(I hope not).

Okay, moving to the next step, step 2, you say you adjusted the "Saturation" slider.  There isn't anything labeled like that, but looking at your picture, I notice that the two bottom histograms have moved, so I played with the slider at the bottom of those histograms, and that moved the lines.  I was able to read the number in the box next to the slider, so I moved the slider until it read 160.  You don't say how you arrived at this number, so I assume this was just a guess also?

Also, in step 2, you show three boxes that have pointers that are touching his arm.  I don't know what these are or what their purpose is.  I notice there are more of these boxes in the last two pictures and they appear to have something to do with his skin color.

I am way past lost at this point, and I also don't understand the need to keep jumping back and forth among LAB and RGB.  I have never used LAB so I have no idea what the A channel or the B channel does.

I gave up after step 2.  You said in your reply that...." this is a typical response to a question you might have while in the class.  not all of them will be this lengthy... ".  If the replies are this vague, then I probably won't last more than the first class.

Sorry Greg, but I need things really explained in detail.  Since I've never used Curvemeister, every term is unfamiliar to me, so detailed explanations are needed if I am to learn to use it.  When I say detailed, I mean something like, "Open Curvemeister, then change your picture to LAB mode.  To do this you need to click on the box on the bottom right that says LAB."

"Once you've done that, you need to increase the saturation.  To do that, you need to click on the bottom histogram, then, move the slider that is directly below that histogram box until you get the amount of saturation you want.  I moved it up to 160 because... (explain the reason why you did)."

So you see Greg, if it's not explained in this amount of detail, then it's no good to me.  Again, I appreciate your reply, as I know it took a while to type that lengthy reply to try and explain things, and I see what curves can do, but I have a feeling that I'm not smart enough to understand them.  We'll see what happens when the class begins. ;)

[imported_julie]

Hi Art

I'm old too. Hang in there. Ask questions as the class goes along and just focus on week by week. Greg knows what he is doing, and the instructions are written for begininers.

My advice would be to let it go for now, just start in week one and have a go. Everything that looks so hard now will be explained step by step. Have fun.

Also dont worry about asking Greg questions. The biggest mistake I made was to be concerned that I would look silly. Initially that stopped me asking about things I just did not get. Greg is patient and a great explainer even when I was a very slow student.

Julie

[ggroess]

Hi Greg!  I appreciate you taking the time to post your technique.  I am impressed with your results.  Mine look pretty bad compared to yours.

Reading your step by step technique, well, I have no idea what you did or what you are taking about.  Your first step, you say "Lab", so I assume you converted the picture to LAB mode, okay, but then you say you adjusted the "exposure".  What is that?  I have never seen any Exposure adjustment, so where do I find that?  Is that the histogram at the top of the three histograms that says "Lightness"? (I noticed that the line in that box has been moved, so maybe that's what you meant when you said "Exposure"?)

In Curvemeister you can access LAB without a profile conversion so when I say LAB I mean that you click on the LAB selector and start working.  In LAB the L is the lightness channel so it equates to "exposure"  to me these are interchangeable.
 

If that is what you meant, then my next question....how do you know where to place the anchor point?  Then, how do you know which direction to move it and how much do you move it?  When I say which direction, I mean, do you move the anchor point at a 90 degree angle to the line?....do you move it straight up?....is it a combination of the two?

The location of the end points is set by a process called "Thresholding" the goal is to find the highlight and shadow points using the CM tool set.  We cover this in class ina great detail but if you want to get started you can read the following article :
http://www.curvemeister.com/wiki/index.php?title=Highlight_and_Shadow_Thresholding


The moves you describe are always possible and with the goals of making the image better you would move them in whatever direction makes the best improvement.    How much is described in the thresholding article.

See, that is what I've read in other tutorials, they just say to move it.  They don't tell you where you need to place the anchor point or how much to move it, they just say grab the line and move it.  I guess you have to just guess at those things right?(I hope not).

Actually, we do not guess on this.  The threshold is very much up to you but it is not a guess.

Okay, moving to the next step, step 2, you say you adjusted the "Saturation" slider.  There isn't anything labeled like that, but looking at your picture, I notice that the two bottom histograms have moved, so I played with the slider at the bottom of those histograms, and that moved the lines.  I was able to read the number in the box next to the slider, so I moved the slider until it read 160.  You don't say how you arrived at this number, so I assume this was just a guess also?

My Bad..you are right there is no label.  The saturation slider is a subjective move that you control;  It only exists in LAB where saturation is controlled by rotating the curves .  We will always push for more color in the image but only to the point where detail starts to suffer.  We cover this in the class work...

Also, in step 2, you show three boxes that have pointers that are touching his arm.  I don't know what these are or what their purpose is.  I notice there are more of these boxes in the last two pictures and they appear to have something to do with his skin color. 

These are the hue clocks.  They are a tool used in CM  to help you visually see the color you are adjusting.  For skin tones the hue clocks should to the best of your ability be pointing just past 12:00 to the 1:00 side.  If they go the other way things are too blue.

I am way past lost at this point, and I also don't understand the need to keep jumping back and forth among LAB and RGB.  I have never used LAB so I have no idea what the A channel or the B channel does.

I think that once you get into the class and learn more about these things the confusion will drop off.  LAB is another color space like RGB or CMYK  In LAB the color is separate from the lightness so it is a great tool for getting the exposure right without messing up the color or...making the color pop without messing up the exposure...A channel controlls the Reds Vs. Greens  B channel controls Blues Vs. Yellows. 

I gave up after step 2.  You said in your reply that...." this is a typical response to a question you might have while in the class.  not all of them will be this lengthy... ".  If the replies are this vague, then I probably won't last more than the first class.

By the time we get theree these will be verry easy to understand ...I hope...I will keep trying if you will...

Sorry Greg, but I need things really explained in detail.  Since I've never used Curvemeister, every term is unfamiliar to me, so detailed explanations are needed if I am to learn to use it.  When I say detailed, I mean something like, "Open Curvemeister, then change your picture to LAB mode.  To do this you need to click on the box on the bottom right that says LAB."

Don't be sorry..There are no dumb questions....I'll be there every week every image...I'll have more information and you'll have the class written materials.

"Once you've done that, you need to increase the saturation.  To do that, you need to click on the bottom histogram, then, move the slider that is directly below that histogram box until you get the amount of saturation you want.  I moved it up to 160 because... (explain the reason why you did)."

So you see Greg, if it's not explained in this amount of detail, then it's no good to me.  Again, I appreciate your reply, as I know it took a while to type that lengthy reply to try and explain things, and I see what curves can do, but I have a feeling that I'm not smart enough to understand them.  We'll see what happens when the class begins. ;)

Well smart enough??  I guess I would say you are smart enough to go looking for help.. that would be the first step...You are smart enough to ask for detailed explanations...that is the second step...I guess all we need to do now is try...

Hang in there Art.  I'll help you understand this...
Greg

[leeharper_admin]

...detailed explanations are needed if I am to learn to use it.  When I say detailed, I mean something like, "Open Curvemeister, then change your picture to LAB mode.  To do this you need to click on the box on the bottom right that says LAB."

"Once you've done that, you need to increase the saturation.  To do that, you need to click on the bottom histogram, then, move the slider that is directly below that histogram box until you get the amount of saturation you want.  I moved it up to 160 because... (explain the reason why you did)."

Don't worry Art - these are exactly the form that the explanations will take once the class begins. The way that the class is structured is that each week you will be able to download a PDF which will explain (in this level of detail) a technique (or series of techniques), along with a set of images to practice the techniques with. During the week you will be able to ask as many questions as you like if anything in the course materials requires clarification. At the end of each week, a 'solutions' PDF becomes available - along with videos containing solutions to the week's exercises (sometimes there are videos to watch at the beginning of the week too - these give you hints, to help you get started).

If Greg's step-by-step for the image you posted is tricky to follow at present, don't worry - come back to it in October and it will make much more sense. ;)

Don't worry about specifics yet - that's what the class is for. You will be able to do everything that Greg did to your image by the end of the course; for now just keep in mind that Greg's correction looks really good, and you will be able to do that very soon. :)

Lee.

[mikemeister_admin]

Thanks for the encouragement everyone!  I am looking forward to the class since no matter what, I have to learn something. :)  I am not bashful about asking questions, but I'd prefer to try and figure it out myself first.  By figuring it out for myself,  I don't forget it as easily.  I find that I have trouble remembering things these days...old age I guess.

Anyway, thanks for all your help Greg, and I'll wait till the class starts before asking any more questions.  I figure that mostly likely, a lot of my questions will be answered during the class, so there's no point in asking questions now when they will be covered in class. 

[mikemeister_admin]

Art,my first week I didn't know how to post images.
below is an image with some anchor points.
the points from 50 back were put there so the line won'tmove(curve) when I adjust point A up or down.
If I pull A down, the line from 75 to the top becomes steeper,making those pixels brighter.
The line from A back to 50 will flatten out  and the pixels will dim a bit.

If I raise the point at 24 the anchors(arrowheads) at 50,30,and10 will confine the effect to the range from25 to 35.
As my raised line nears the horizontal bad things start to happen,posterization,etc.
Hope this helps,GregM