Let’s see what effect the “resolution” and “default page size” parameters produce when ink (toner) coverage of a document is measured in APFill Ink Coverage Calculator.
When a document is opened, APFill uses the GhostScript library to convert a PDF (or PS) file into color-separated bitmap TIFF files to measure ink coverage. This is when the “Resolution” parameter is used. The higher it is, the higher the conversion quality and lower its speed. Therefore, when this parameter is increased, the speed of image processing goes down, but the coverage calculation accuracy is improved. The opposite is also true – when this parameter is decreased, the processing speed grows, but the accuracy is affected. As a rule, setting the resolution to 300dpi will give you decent processing speed and sufficient measurement accuracy.
The default ”Resolution” value can be set using the “Options” menu of APFill. You can also set a different value of the “Resolution” parameter after opening a document for re-conversion with a new resolution.
Some users ask us if APFill supports documents with arbitrary page sizes and not just the ones set by the “Default Page Size” parameter (A4,A3,etc). The thing is that the “Default Page Size” parameter is used ONLY if the page size is not set in the PDF/PS file. If the page size is specified in the file, APFill uses this value and DOES NOT use the “Default Page Size” parameter. Therefore, APFill can calculate ink coverage of pages of ANY sizes.
Please note that APFill calculates ink coverage as a per cent value of the page area. That is, if a page has a standard A4 size and the result of filling with any color (CMYK) is 5%, this is not the identical to a 5% filling of an A3 page. Since the area of an А3 sheet is two times larger than that of an A4 page, its 5% fraction will be correspondingly larger. Therefore, 5% A3 = 2*5% A4 = 10% A4.
In general, if you need to calculate the X% coverage of a page with an area of S1 and you know the Y% coverage of a page with an area of S2, you can use the following formula:
X% = Y%*(S2/S1);