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í [As Is] keeps the voxel values in the copy as the same type as in the original underlay; you can also change the voxel values to be stored as:
§ [Byte] (integer values: 0..255) Þ 1 byte each
§ [Short] (integer values: -32767É32767) Þ 2 bytes each
§ [Float] (fractional values) Þ 4 bytes each
§Bytes and Shorts make the most sense for ROI masks, where you are essentially attaching labels to voxels
åClick on [Choose Dataset], select the dataset you want a copy of (e.g., the anatomical underlay), and then press [Set]

¥Step 2: Drawing the ROI (or ROIs):
HChoose the value to draw into the anatomical overlay dataset (recall that all values in the copied/blank overlay dataset are zero at this point)
åIf you drawing only one ROI, then the default value of 1 is good
åIf you are drawing multiple ROIs, then you should choose a different numerical value for each so that they can be distinguished later
íPencil and paper are our friends -- write down which number corresponds with which ROI for later recall!
HChoose the drawing color
åThis is the color that is shown while you are drawing
åColor choice is only important to give a good contrast with underlay, so donÕt obsess too much over this