Every earlier optical row in this book fixed magnification at four and only ever scanned the tile count. This scan holds sample length (3 m) and pixel count (6) fixed and checks three magnification values instead: magnification 2 gives image length 6 m and pixel size 1 m; magnification 4 gives image length 12 m and pixel size 2 m, exactly matching chapter two's own single checked example; magnification 6 gives image length 18 m and pixel size 3 m. Magnification alone stretches the image and coarsens each pixel's physical footprint.
Every earlier optical row fixed magnification and scanned tile count; this scan holds sample and pixel count fixed and scans magnification itself. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Every earlier optical row fixed magnification at four
Chapters two and six both kept magnification fixed at 4 and only ever varied the tile count. Here the sample length stays 3 m and pixel count stays 6, but magnification itself changes: at 2, the image length is 6 m.
Limage=3m⋅2=6m
Magnification scales both the image and the pixel size
The sample and pixel count never change across these rows. Magnification alone stretches the image length and, with the same pixel count, the physical size each pixel covers.
mag246Limage6m12m18mpixel size1m2m3m
The highest magnification gives the coarsest pixel size
At magnification 6, the image stretches to 18 m and each of the same 6 pixels now covers 3 m of physical sample.