The Brush and the eraser tools are used to create (using the brush)
and remove (using the eraser) masks or to edit masks. Masks is what we
we call shapes that are more complex than polygons and bounding boxes. A
mask is set on a pixel-level, and is used for when you need
pixel-perfect level annotations.
The brush tool can be selected by pressing "B".
The eraser tool can be selected by pressing the toggle in the top navigation after first having selected the brush:
...or by pressing "E".
When selected, you use the brush as you would use a brush in any
graphical editing software (for example Microsoft Paint). Move your
mouse to where you want start painting, click and hold down the "left
mouse-button" and then drag the mouse pointer to paint.
You can control the width of the brush by adjusting the slider in the
top left corner or by pressing , (to decrease width) and . (to increase
When using the brush, most users often start by first painting the outline before filling in everything in between. In Hasty however, you don't need to fill in your annotation manually. Just press the "Fill closed path" button in the tool menu or press "Shift" + "F". This will fill in all of the area in-between as long as the outline is 100% closed.
Don't underestimate this feature. Many times, people reject pixel-perfect annotations and opt for polygons instead as they are quicker to do. But if you only have to draw an outline, the time per annotation goes down quite a bit to similar levels.
When using the brush, you are creating one annotation at a time. That
means that from when you start using the brush, until you convert the
selection you made with the brush into an actual annotation, everything
you paint will be part of one annotation. This is also true even if the
areas you have painted or not connected. In theory, you can paint
hundreds of stand-alone areas and then convert all of them to one
annotation. This is important to know when you are annotating objects
that have occlusion.
When using the brush, sometimes you want to remove pixels that you
have painted from your current selection. To do so, just press "E" (or
click the icon in the toolbar) to switch to the eraser. As the brush and
the eraser are complimentary tools, the selection you have made with
the brush will not be removed. Instead, you will be able to erase parts
of your current selection in the same way you would add to the selection
when using the brush. When you have finished erasing, you can switch
back to the brush by pressing "B".