This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
>From: Dave Santek <address@hidden> >Organization: Space Science & Engineering Center >Keywords: 200110011803.f91I35128630 McIDAS-X grayscale cursor values Dave, >JohnB reminded me that the graphics take some of the levels, so >the original 0 to 255 gray levels get compressed into (256 - graphics_levels ) >space. Also, the cursor uses at least one color. This means that there is never a one-to-one mapping between display object values and original image brightnesses. This is not a huge problem for display level tracking, but it can be if one then tries to take that value and return its calibrated (e.g., T) equivalent. Even though I have not yet had time to look back through the code, I have the impresion that the situation is even more complicated than that. What is niggling my memory is something to the effect that the frame object values are indicies into the frame enhancement, not brightnesses or scaled brightnesses. Tom