Ceci est une ancienne révision du document !
Website: https://rawtherapee.com/ Version 5.6 Price: Free!
Before I continue this short series on Rawtherapee, know that editing large RAW photos requires a lot of memory. I recommend 8GB or more. This simple picture we have been playing with, is taking up 1.6GB of memory on my computer inside Rawtherapee.
I hope you kept the last picture we were working on as we will be continuing where we left off.
March 2020 it seems wesaturate.com has broke: the file is now hosted on the FCM servers here: https://bit.ly/2WNVfPf
Last time I had you oversaturate the picture and turn it into mobile phone wallpaper.
The reason I actually had you dramatize the picture was to draw your eye to the different light and dark sections of the photograph that became very obvious when you did so. You can use these ‘bands’ as a guideline for where to put your edits, and at which angle they should go. Did you actually try the homework? Well, this is another dirty trick you can keep in your tool belt.
Like Darktable, Rawtherapee also supports L*a*b adjustments. Click on the first tab or press Alt+E and scroll down to L*a*b Adjustments. Now, don’t confuse them with the lightness, contrast & saturation in exposure. This is not the same thing.
In the L*a*b adjustments, you will see that each channel has its own curve. You can choose a different curve, but they all start on linear. You can use the dropdown arrows on each of the three to change them. Directly below, you will see six more tabs that can be adjusted. ‘LH’, ‘CH’ and ‘HH’ each has a horizontal line in them; to activate, drop these down to equalize. What you now have is somewhat similar to a music equalizer, except in colors. LH is luminance to hue, CH is chromaticity to hue, and HH is hue to hue. Phew!
You can adjust these individual colors by grabbing a point and dragging it up or down. Unlike a music equalizer, you can also define curves in between. You can even ‘create’ colors in between other colors and manipulate those. What makes it really powerful is the little color-picker tool. You can select an area in your picture you want to manipulate, by color! Should anything go wrong, there is a reset in the top right in the first row of tabs, named curves. The last row ‘CC’, ‘LC’ and ‘CL’, are curves again. These basically allow you to move your histogram and manipulate color intensity.
Now that you know what-is-what and where the buttons for each are, let us manipulate our picture.
Go to ‘LH’ and turn on the equalizer. BEFORE you adjust anything, make sure your mouse is on a flat surface and you are holding it comfortably. The reason I say this, is that adjusting a color up or down, you will get lateral movement. Typically you try to avoid this unless it is intentional. You can also employ a ruler or box or other straight object, to rest the mouse against. Go easy on the adjustments, you can create artefacts by being heavy-handed. Hint: do not neglect green, even if there is no green in the image. Now if you have been playing, you would have realised this works in the opposite. If you want less yellow and the sky a little brighter, drag upwards. If you want more yellow, drag downwards. This is because you are actually playing with the brightness, so to speak, and not the saturation. As I pointed out, you can create artefacts, but generally, you will find that moving these sliders creates noise, and the compounding of this noise is what creates artefacts. So after making your adjustments, you need to go to the second tab, Alt+D and go to noise reduction. Make sure the color space is set to L*a*b. Now fix it here.
We are lucky that our boat has a rainbow on the hull, keep your eye on this when you adjust the color space. As our picture is mostly blue, keep zooming in to 1:1 on the sky and look at what is happening there.
Now that you have played with the brightness (luminosity according to hue) , now move to color, or chromaticity according to hue. Now, in this one, the saturation works in the upward direction. As I mentioned before, now you have the opportunity to adjust Cyan to adjust your blues. I want you to try to adjust Blue upwards. You will see how ‘kitch’ the picture becomes. However, if you drag Cyan, it enhances the overall blues in your picture. Remember to turn off the tool every few minutes, so you can visually track your changes. I say this, as sometimes it seems like you are not making a change, but turning the tool off reverts to the original image and your brain immediately catalogues the changes!
Okay, now we move to HH. The adjustment in HH actually works sideways when you drag up and down. Dragging a point down moves the hue to the left, and dragging upwards moves the hue to the right.
And that is the secret of the confusing L*a*b adjustments. LH up is down, CH works like you would expect, and HH up is left and down is right. Now this is speaking in terms of color and explaining by crayon. If you need to understand, re-read each section, for what it actually does. Also, practice to understand why each slider does what it does.
Tips: Remember to sit up straight and look at your monitor head on. A tilted monitor or skewed viewing angle can make a difference. Make sure your brightness and contrast settings are at levels that make things look natural. High brightness and low contrast have caught me out time-and-again working on someone else’s display. Less is more, work in small increments, unless over-the-top is what you were aiming for.
Please send all comments and corrections to: misc@fullcirclemagazine.org