All ACAS experiment-sets require the user to enter the pixel per µm resolution of the uploaded images (i.e. the number of pixels for each µm of distance in the image).
This is a critical measurement and is used in two ways:
a) the ACAS software reads the number of pixels in the image, but it cannot know how many pixels a typical cell will occupy without this distance factor. This allows the algorithms to optimize the detection of structures.
b) the ACAS software reports its findings in terms of µm lengths and areas. Without this factor, it would report in pixels and leave the final conversions to µm to the researcher.
Resolutions lower than 0.4 pix/µm typically do not provide enough visual information for successful analysis. The typical range we see is 0.5 to 2.0 pix/µm.
Advanced Guide to Pixel Resolution
Advanced Guide to Pixel Resolution, provided by ibidi
Please note the ibidi technical note uses µm/pix whereas ACAS uses pix/µm.
So to get the units required by ACAS, simply invert the result ( 1 divided by ibidi-number).
The Simple Calculation
The (pixel / µm) resolution is calculated by :