General Comments About Some Toolbox Widgets
This article is important - some things may sound obvious if you are an experienced user, but some things are guaranteed to be unknown to you and knowing them will let you use RawTherapee faster and easier. Take five minutes to read it!
The panel on the right side of the preview contains the controls for all the tools available in RawTherapee. They can do a lot, perhaps even more than you ever may want to! If you're new to RawTherapee or new to raw processing in general, don't feel overwhelmed, as there is no need to touch all those sliders to get decent results. In this section you'll find a brief description of what all those tools are for, tab after tab.
A panel is a foldable element which contains buttons, tool, histograms, etc. The Editor tab has three main panels: the one on the left which contains the history, the one on the right which contains the tools, and if you're in "Single Editor Tab Mode" the one on the top which contains the Filmstrip. They can be hidden away from view with the little arrow buttons or using keyboard shortcuts, making more room for the image preview.
You can use the mouse scrollwheel to safely scroll up/down in the panels without fear of accidentally changing a slider, because RawTherapee requires that you hold the Shift key while using the mouse scrollwheel if your intention is to manipulate a slider or cycle through the options in a drop-down menu (called a "combobox").
RawTherapee has many tools, and each tool has one or more controls, or widgets, which you can turn or move or push or slide to make the program do something. They are divided up among the Exposure, Detail, Color, Wavelet, Transform, Raw and Metadata tabs, for example the Exposure tab has tools which deal with exposure, such as the Exposure tool and the Shadows/Highlights tool, etc., the Color tab has the White Balance tool, and so on.
Because there are so many tools, you will notice that vertical screen space is precious, and you will at times hide some tools to see others. RawTherapee makes this easy. Right-clicking over a tool's title expands it and collapses all other tools of the same tab. You'll learn to love this shortcut when you consider the time you would have spent on folding tools manually...
To the left of most tools' titles is a button which lets you enable or disable the corresponding tool. The concept of being enabled or disabled doesn't always make sense - for example what would it mean for the White Balance tool to be disabled? There must always be some white balance being used - so these tools instead of an enabled/disabled button just use a triangle symbol to let you expand or collapse them. Lastly, you will notice that in the File Browser tab if you select several photos then the power button can have a third state which looks only half-enabled - this state, called "inconsistent", means that the tool in question is not enabled in all of the selected photos.
Each slider has three values in memory:
- The current value, when you move the slider to any position,
- The 'default' value, the one that the programmer has set as default. It can be called back by clicking on the 'Reset' button,
- The 'initial' value, which is the value of the profile used when the image was loaded in the editor. It can be called back by Control-clicking on the 'Reset' button.
As written above, if you want to move a slider using the mouse scrollwheel, or cycle though a combobox, make sure you hold down the Shift key while doing so, otherwise instead of moving the slider you will scroll up/down in the panel.
RawTherapee has three types of curve editors – for Threshold Curves, Tone Curves and Flat Curves. They are discussed below along with some general pointers.
Threshold Curves are the simplest. They are used to tell a RawTherapee tool the tones (or hues or saturations values) that you want processed (or processed differently).As an example, consider the Threshold curve editor on the Detail -> Sharpening tool.
On the top right is a reset button that will reset back to default.
Warning: resetting the curve is considered a curve modification, so if you've just modified the curve and mistakenly pressed the Reset button, there's no way to bring back your curve. (Ctrl-z will go one step before in the History list, not in the curve's edition). This comment applies to Tone and Flat Curves as well.
You may have noticed that Threshold Curves actually consist of a few straight lines rather than a curve. If this bothers you, you might want to take a break before moving on to Flat Curves.
General Comments on Tone and Flat Curves
Tone and Flat Curves are more powerful than Threshold Curves and have some controls that aren’t needed on Threshold Curves.
Each Tone or Flat curve editor has a button to select its type. It's a so-called 'Toggle' button, i.e. it will stay pressed or stay released after each click on it. Toggling on/off the curve's button will respectively display/hide its associated editor. This is very handy and saves a lot of space when handling groups of curves (e.g. see the Lab curve editor).
These curves have a Reset button on the right which will reset the displayed (or pressed button) curve only.
They also have a pipette tool and a node in/out value input tool, which deserve sections of their own.
Most curves in RawTherapee have a pipette button . This feature is a great way to target specific hues, tones and areas of a particular saturation, and using it will make tweaking your images easier and faster. Let's say you want to change the purple hue of a flower, to make it more red. Without the pipette, you would have to guess the exact shade of the hue, else the affected range of hues would be too wide and you might end up changing something you did not want to change. With the pipette, you simply click on the flower, and a point appears in the relevant curve. You can adjust this point to your liking, knowing it represents the exact hue you want affected.
The pipette tool must be activated for each curve, simply by clicking on it. Now when you hover the cursor over the main preview you will notice that a vertical line (or even four of them) appears in the curve panel. This line represents the value of interest of the pixels you're hovering over. To place an adjustment point in the curve for the value you're hovering over, Ctrl+leftclick in the preview, and a dot appears in the curve. You can adjust that point without leaving the preview area, just keep holding the left mouse button after you placed the curve point, and moving the mouse up and down moves the point up and down. Remember that holding Ctrl while editing a curve point decreases your mouse speed so that you can very finely adjust points, but usually you will not need this, so after Ctrl+leftclicking to place the point, let go of Ctrl, but keep holding the left mouse button.
To deactivate the pipette, either right-click anywhere in the preview area, or left-click on the same pipette's button again.
You do not need to deactivate the previous curve's pipette to use it on a new curve, just activate it as usual, and the old one automatically deactivates.
Curve Node In/Out Value
Introduced in version 4.2.192, each curve has a node in/out value input tool. You can use this tool for example to match node values on a photo of a color target with known patch values.
The tool works with nodes, and the most likely way you will create these nodes is by using the pipette. For this example, we will start with a curve without any nodes and create some using the pipette. Click the node value editor button next to the curve, and also click the pipette's button . You will now see "I" (in) and "O" (out) values displayed under the curve. They correspond to the point under the mouse cursor if you hover it over the curve. Hover the cursor over the image preview. Since you activated the pipette, you can Ctrl+click on a spot in the preview area to place a node which corresponds to that spot's value in the curve (whatever that value may be - for example for the L* curve, the value is the internal value of the pixel you've placed the spot over at that point in RawTherapee's internal pipeline, and the output value is that value affected by your curve). Do that, Ctrl+click on a spot in the preview. A node appears in the curve. To edit the node's in/out values, right-click on the node. It turns red with a red ring around it. Now you can edit the in/out values and see the node move in real-time. Once you are done editing, either right-click anywhere inside the curve area other than on the node to go out of node editing mode, or just click the node value editor button again to deactivate it.
Tone Curves are somewhat misnamed since, while some are used to adjust tones, others are used to adjust saturation, chromaticity or other properties. Their purpose is to map an input value (on the horizontal or X axis) to an output value (measured on the vertical or Y axis). If Math isn’t your first language, don’t worry – after a little playing with them, everyone seems to quickly develop an intuitive understanding.
As an example, consider the figure to the right – part of the Exposure tool. The left part of the graph represents the darker tones, the right part represents the brighter tones of the photo. You can see that the bottom left of the curve has been moved up. This will cause dark areas to be boosted. Similarly the top right of the curve has been pulled down, cutting back the bright areas.
The figure shows the curve type drop down. Tone curves allow four different ways of manipulating the curve:
- Linear: The default type - a straight line that results in no change to input values. The mathematically inclined may observe that it is a graph of y=x. The rest of us just set the control to linear to “turn off” the curve.
- Custom: The type most commonly seen in other software. Click to drop a control point anywhere on the curve and then drag the control point to change the curve’s shape. The top-right point represents the brightest areas in the photo. Drag that point vertically down to make the highlights less bright; move it horizontally to the left to make bright areas brighter, perhaps at the cost of some overexposure. The bottom-left point represents the darkest areas in the photo. Move that point horizontally to the right to make the photo darker, perhaps at the cost of some underexposure. Move it vertically up to make the darks lighter.
- Parametric: Allows you to use sliders rather than dragging the curve directly. For the Parametric curve type, clicking the right mouse button over the zone selector () will reset the handles' position to their default values. (The global reset button will reset them too.)
- Control Cage: At first sight this curve type looks very much like the Custom curve, but there are some differences. With the Custom curve, the curve touches all the control points. This is not the case with the control cage curve – the control points attract the curve towards them but the curve doesn’t actually go through them. Another difference is that the control cage allows for a straight section of the curve, while you can't do this with the custom curve. The cage curve needs at least three points for that (so five in total). Holding down the Shift key while dragging a point will help you to easily create a straight line by snapping the point to the line made by the previous and next point (displayed in red by the 'snap to' tool). Many users prefer Control Cage type curves to the alternatives.
The Flat Curve
A number of tools in RawTherapee use the flat curve:
It's very simple to use once you understand it, so let's use the HSV Equalizer in the Color tab as an example. Click on the drop-down icon next to the H(ue) button and choose "Minima/Maxima control points" . You'll see six dots on the horizontal line in the middle and six vertical lines that cross these dots. Notice that those lines are colored; from left to right: red, yellow, green, aqua, blue and magenta. Now click on the very left dot (the cursor changes into a little hand) and move it slightly upward and downward. Result: red colors quickly change to green, blue and magenta as the cursor is moved up, and to pink, blue and green when moved down.
Notice that a new horizontal line appears when you start dragging a color point, and see how its color changes. The vertical axis represents input colors, and the horizontal axis output colors.
When you click and drag a vertical line (the line, not the point!), the very first movement will determine the kind of move: vertical or horizontal (so take care with this first movement if you want to have a predictable result). If you want to move the point in both directions at the same time, then click and drag the point itself. To move the point only in one direction (only horizontally or only vertically) you can use the 'snap to' function by holding down the Shift key while moving the point.
It's easy to see if a point is on its neutral value (i.e. on the middle line) because the color of the point will be green. As soon as you move a point off its neutral value, it changes color to black.
The HSV Equalizer wraps around on the horizontal axis, so the very right vertical line equals the very left line. You can see this by dragging the red line on the left side a bit to the left. Now the left point of the graph is at the same position as the very right point. Holding the Shift key while dragging a point prevents it from wrapping around the horizontal axis, which can be useful in preventing accidental curve steps in hard-to-see places at the edges.
You can delete points by dragging them out of the editor field. You can add points by clicking somewhere on the curve. When you place the mouse on one of the points, you see a yellow and blue indicator. Place the mouse on the yellow one and the cursor changes into a left arrow. Now you can drag this point to the left, to change the slope of the curve. Ditto for the blue indicator.
To get an idea how this editor works, delete all but two colors (e.g. red and yellow) and move the graph around, change its slope and see what happens to your photo.
Reset the Hue curve to "Linear" (no changes) by clicking on the reset icon next to the Value button. To compare the effects of the Hue curve with linear: switch between "Linear" and "Minima/Maxima control points" in the drop-down menu next to this button, or use the history list on the left side of your screen.
You can save a curve for later use by clicking on the disk button. Note that only the actual (shown) H, S or V curve is saved, not all three at once, so don't give your curve a name like my_hsv because it doesn't describe whether the curve inside it is H, S or V, but instead name your saved curve files something like my_hue, my_sat and my_val. The extension will be added automatically, ".rtc".
The Preview Area
The preview is designed to show you the most realistic result possible, however one must keep in mind that the larger an image is, the longer it takes to process. For speed reasons, the preview of the effects of most tools is calculated not on the full-sized image (which would take exactly as long as saving the image, making using sliders and curves impossible), but on the preview image which is of the size of your preview area. Many tools, such as the Exposure tool, can be applied to an image of any size, and their effects will be identical regardless of the size of the image they are applied to. However some tools are size-dependent, for example all of the tools in the Detail tab, which means if you apply one of these tools to a full-sized image and to a smaller version of that image, and then downscale the full-sized image to the smaller image's size, the two images won't match. For reasons of speed, RawTherapee must use the small preview image so that your tool tweaking experience may be fast and fluid, but this means that the effects of size-dependent tools would not be accurate when applied to a small zoomed-out preview. We made the decision to either disable the preview effects of these tools entirely at zoom levels less than 100%, or to keep the preview effects active but to warn you that what you see at zoom levels less than 100% may be inaccurate depending on the tool settings (for example Tone Mapping and Wavelet may be accurate at zoom levels less than 100% or they may be inaccurate, depending on their settings). You will know which tools these are because they are marked with a "1:1" icon next to their names. RawPedia explains how accurate the preview is for all affected tools on each tool's page.