Firefox developers don't know how to print in grayscale

[ValdikSS]

https://github.com/mozilla-firefox/firefox/blob/aa1a3e3cd5f618cb244c803cb4f26d4e29007935/widget/nsPrinterCUPS.h#L148-L179

Michael, maybe CUPS can suggest to Mozilla something better than that?

D [07/Sep/2026:21:45:25 +0200] [Job 26] argv[5]="PageSize=A4 EPRendering=None XRXColor=BW INK=MONO SelectColor=Grayscale HPColorMode=GrayscalePrint ProcessColorModel=Mono BRMonoColor=Mono CNGrayscale PrintoutMode=Normal.Gray BRPrintQuality=Black Collate Duplex=None ColorMode=Mono CNIJGrayScale=1 ARCMode=CMBW print-color-mode=monochrome OKControl=Gray ColorModel=Gray XROutputColor=PrintAsGrayscale BLW=TrueM job-uuid=urn:uuid:6d93adb4-bea2-36ab-64ff-80eec0faf5a5 job-originating-host-name=localhost date-time-at-creation= date-time-at-processing= time-at-creation=1788810325 time-at-processing=1788810325"

[michaelrsweet]

The correct option/attribute to use is "print-color-mode" (keyword), which is mapped to the corresponding PPD option and choice:

• 'auto' for automatic color/grayscale
• 'monochrome' for grayscale
• 'color' for full color
• 'bi-level' for B&W (typically for barcodes and other strictly black and white output)

Ultimately they should be using the CUPS destination API for printing, which sticks to IPP Everywhere attributes and values. This API is available on macOS and any Linux/*BSD/Unix platform running CUPS 1.7 or later. There are some CUPS library enhancements that aren't available until later versions of CUPS but you can easily test for them at compile-time and even use a newer version of the CUPS library with older versions of CUPS if you like - it's all just IPP under the covers...