Advanced use of the Curve Tool
September 28, 2011 6 Comments
The Curve Tool in Capture One is a very powerful tool for precise control of the tone mapping of an image. Even though the Exposure Tool also provides sliders for controlling the tone mapping, you sometimes need a more advanced tool to achieve a specific goal.
You can use the “Pick Curve Point” cursor tool to place a point on the curve by clicking directly in the image and you can fine tune a curve point by using the scroll wheel on your mouse.
The left image is straight out of the camera. The right image has been corrected in Capture One with the Curve Tool and the Color Editor.
To enhance this image, I first used the Color Editor to boost the colors a bit, but I found that the rocks in the foreground needed more contrast.
If I use the contrast slider in the Exposure Tool to add contrast to the rocks in the foreground, they just get darker. The built-in contrast correction adds contrast to the image – but not in the way I prefer for this image.
In the Curve Tool, I can see the location of a tone represented by a vertical line underneath the curve. Moving the cursor around on top of the rocks in the foreground, I can see that the first spike in the histogram originates from these rocks. In order to add contrast for these rocks, I start by adding a curve point by simply clicking on one of the rocks with the “Pick Curve Point” cursor tool.
To increase the contrast, I add another curve point. This time, I just click on the curve a little below the first curve point. I can drag this point with the mouse, but it can be done with much more precision by using the scroll wheel of the mouse. Place the cursor beside the last added curve point, and you will see that a horizontal orange control line appears. If I turn the scroll wheel, I can move this curve point up and down very precisely. To add contrast, I need to bring the curve point down turning the curve into an “S” curve shape. The maximum steepness of the curve, which creates the contrast effect, occurs exactly where it is needed to give contrast to the rocks.
Curve points can also be adjusted horizontally. To do this, I place the cursor vertically over a curve point and a vertical orange adjustments line appears.
Hi Professor,
Three questions:
What do I gain from this curve tool working directly on the raw file (if that is what it do) compared to the curve-tool in Photoshop working on the C1-generated tiff-file. Is there a principle quality gain in using C1 at this earlier state?
In Photoshop I can flip a Curves layer on and off to see, if the local adjustment (in this case to the stones) is affecting the surroundings. How is this done in C1 without having to redo the settings?
In Photoshop I can even fine-tune the local adjustment by reducing the opacity of the Curves layer. Is there a similar function in C1?
Hi Eigil
When working with the Curve Tool in Capture One, you work directly on the RAW data in full bit depth so you can do much more dramatic changes before the image data starts to break up compared to working on the data later in Photoshop. If you typically do many corrections in Photoshop, I recommend that you use 16 bit pr channel when you process the image. I typically do as much as possible in Capture One and most often I have no need for further tweaks in Photoshop.
For most of the tools in Capture One, you have the ability to do a temporary reset of a tool. You do this by pressing Alt + the tool reset button(third icon in a tool header bar. Most often, I just create an extra variant so I have 2 version of the same image, one with the correction and one without. I can then compare the images side by side or I can flip between the 2 images.
In Capture One, you do not have the option of changing the opacity of an adjustment layer. Instead you have the ability to do very accurate fine-tuning of slider or curves adjustments by using the scroll wheel on the mouse. Just place the mouse over an adjustment slider and use the scroll wheel to fine tune the value. This way you can focus on the effect on the image. I will typically drag a slider and when I am close to the position that best works for an image, I will release and fine-tune with the scroll wheel.
Best Regards
Niels
Hi Niels,
1.
“..you work directly on the RAW data in full bit depth so you can do much more dramatic changes before the image data starts to break up compared to working on the data later in Photoshop.”
Believe me or not. This answer is what I have wished to hear for a while, as it would justify my staying in C1 as long as possible. Why has this argument not yet been spread as a promotional argument?
To exclude all doubt: Is this also a fact, if I (as I have done for some time now) generate a 16 bit TIFF from C1 and do e.g. the curve-adjustment in Photoshop on that generated TIFF?
To my best knowledge Photoshop’s internal format is close to TIFF though finally saved as PSD, and I guess that C1 is also working on a internal format (like TIFF), as it would be infeasible to work directly on each existing RAW format.
So, in my opinion a 16 bit TIFF would react in the same way on a certain adjustment, regardless of the change being made before or after the transfer to Photoshop.
I hope I am wrong, and in that case you should tell the whole world the reason why you apparently are trying to create a new Photoshop inside C1 – seriously.
2.
Thank you for this key combination. I should have found it myself, as I have needed it for a while. Even when I re-scan the User Guide (PDF) as well as the Online User Guide, I can’t find the combination. It must be there, I am sure, but I have difficulties with those two documents.
3.
The scroll wheel works nicely too. Thank you for showing.
Hi Professor,
Could you please explain the input and output readings and what they mean and what profile they are reading from.
Also when you picked on the rocks the input and output show a value of 135 yet the point right next to it you dropped had a value of 21
Hi Robert,
The numbers in the Curve Tool refer to the internal RAW color space which is a Gamma 1.8 space, like the Prophoto RGB color space.
For the image with the Curve Tool showing input=135 and output=135, these numbers do not refer to the intensity value of the rocks. The input and output numbers in the Curve Tool only updates when you move the cursor inside the tool. When you move the cursor outside of the curve tool, the readout values just shows you the last (input, output) value that was updated (for the Mac version). The first curve point from the pick on the rocks was input=51 and output=51, the second curve point was input=27 and output=21. When you place the cursor below or beside a curve point you will get the orange adjustment line and you will get the input and output values from the “active” curve point.
All the best,
Niels
Regarding item #1 in my Comment above (regrettably closed for further dialog):
Niels, I take the absence of an answer to my comparison as a confirmation of this:
If I make an adjustment to any raw file inside C1, I actually work on an internal 12-16 bit C1-format (that could be a TIFF-like format).
So, if I generate a 16 bit TIFF file from the same internal C1-format and make a likewise adjustment in Photoshop, there is actually no difference in bit-depth and robustness of the data.
Please correct me, if I am wrong.
If I am right the direction of making more and more Photoshop-like adjustments in C1 must be for the group of photographers that own C1 but are without Photoshop.
How many are they?
I realize that it would be more convenient for you and PhaseOne if people just shut up and bought the beautiful products. But I really would like to know, why I should stay in C1 a little longer that it takes to convert a raw file for Photoshop?