NIH Image is Wayne Rasband's historical image-processing program for the Macintosh, preceding ImageJ. Its official documentation describes image acquisition, editing, filtering, calibrated measurements, stacks, a macro language and plug-in extensions.[ref][ref]
NIH Image documentation. About NIH Image; manual Introduction and Overview
One concrete representation choice explains why software history matters for interpreting old results. The manual describes internal pixels as unsigned 8-bit values and import of 16-bit data by rescaling to 8 bits. It also documents the convention of displaying value 0 as white and 255 as black; screen appearance and stored numerical values are distinct.[ref]
NIH Image documentation. Manual Introduction, Overview, Images
For an original chosen conversion model, suppose a high-bit-depth image uses values from 0 to 4095 and is mapped to 8 bits byThen . Two distinct recorded values become identical, so no subsequent measurement of the converted image can recover their difference. This is a stated quantization model, not an assertion about an undocumented rounding detail in NIH Image.
Keep the original data and the scaling rule when comparing legacy measurements. Spatial calibration is a separate operation: changing a length-per-pixel setting does not restore discarded gray-value information. The manual's analysis workflow selects a region of interest, computes measurements and records results, making those representation and selection choices part of a reproducible calculation.[ref]
Articles by others on the same topic
There are currently no matching articles.