Brightness and color (and opacity) - ekatrukha/BigTrace GitHub Wiki

You can show "Brightness and Color" dialog by using shortcut S:

Single channel

This is an example of a dialog for a single channel. It uses range sliders (and one can pull the range by dragging the middle interval).

A standard "brightness" here is now called "LUT range", it maps image intensity values to specific colors. This mapping can be done non-linearly by adjusting "LUT γ", gamma value (a power-law).
In addition to color (LUT) mapping, one can also independently change the opacity of voxels using the alpha "α range" (with a corresponding "α γ" gamma adjustment slider below). This feature is useful mostly for volumetric rendering and not so much for maximum-intensity projection.

Button "set view colors:" allows to specify LUT color.

A checkbox on the left is used to synchronize the top pair of sliders (LUT) with the bottom pair (α), but not the other way around (see video below). In the beginning, it is usually helpful to find a proper intensity interval/gamma when they are synchronized and later fine-tune the opacity.

The initial min/max range in the sliders spans the whole intensity range, but you can change it using >> button on the right.

Since usually, the dataset's range is smaller, it makes an adjustment by dragging sliders much easier.

Multiple channels

If you have two (or more) channels, there would be two (or more) boxes, corresponding to each channel:

Using "set view colors:" buttons at the bottom/left you can assign color LUT for each of the channels.

The checkboxes on the right part of the box allow you to group channels together and use a single box brightness adjustment for all grouped channels.

Visibility & Grouping

An alternative way to change brightness/contrast for one or multiple channels or to switch some sources on/off is to use Cards panel on the right side of BigVolumeViewer canvas. This panel can be extended using shortcut P (and collapsed with ⌃ Ctrl + P).
Or using arrows at the middle of the right edge of the canvas.

By default Display mode "Fused" mode shows all active channels (otherwise just current).
You can toggle channel (source) visibility with corresponding checkboxes at the Sources inset. It can be handy to focus on one channel at a time. A similar brightness/contrast panel per one source is displayed at the bottom of the inset.

Groups panel inset allows you to create a group of sources/channels and change their parameters simultaneously. In this case it is a group of sources, not ROIs.

NB: The channel for ROI selection/Measurements is specified in the BigTrace window "Active channel" box. Even if the channel is "not active" in this dialog, BigTrace will use its intensity volume to create/measure ROIs.