> For the complete documentation index, see [llms.txt](https://janelia-flyem.gitbook.io/neutu/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://janelia-flyem.gitbook.io/neutu/2d-proofreading/2d-visualization/2d-viewer-for-grayscale-and-segmentation.md).

# grayscale and segmentation

The user can zoom, pan and change planes with either the keyboard or mouse. These operations will be faster if segmentation is toggled off.

Upon viewing NeuTu's main window the segmentation window is fixed in the x-y view. The user must drag or pan the grayscale underneath the window to view the segmentation in that region.  Users can toggle between the grayscale image and pseudo-colored segmentation using keyboard shortcuts (**F key**) or the toggle buttons on the menu bar.

![](/files/-LtDI_fylAd7MClctXZ0)

Segmentation can be viewed in two modes. In the normal mode, each body is colored and the selected body is white. In the highlight mode, the selected body is colored and user can see the gray scale imaging surrounding the selected body.

{% hint style="info" %}
Not that the selection behaviors under the normal and highlight modes are a little different. Under the normal model, mouse click on a body always clears previous selections and only selects a new one, while under the highlight mode, mouse click adds the new selection to the current selection list.
{% endhint %}

## Segmentation Coloring

The default coloring of segmentation is trying to give each segment a unique color. In reality, the number of segments is usually much larger than the number of colors distinguishable by eyes. As a result, it is possible that two adjacent segments may have very similar colors that can cause confusion. For this kind of problem, we can try the 'Random' color map option:

![Segment Color Randomization](/files/-M746KzbhFbFlmQtJite)

To customize colors for certain groups of segments, we can use the 'Sequencer' option, which works together with the [sequencer](/neutu/sequencer/body-coloring.md). The 'Sequencer+Normal' works in a similar way, except that it will show unspecified segments in random colors instead of with complete transparency.


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