Output in 1-bit-color mode

Does Retrobatch have a 1-bit-color output option? The one that Photoshop calls “bitmap” – each pixel either black or white, no grayscale in between?

To be specific: Grayscale images with a threshold or a matching color profile won’t do the job. Those look like 1-bit, but technically still are 8-bit (or more) will get rasterized when processed for print, resulting in jaggy lines.

Adobe handles 1-bit-images separately and offers higher resolution and different compression for PDF embedding. Without getting into politics here, I’m looking into Adobe alternatives, and the Affinity suite completely lacks 1-bit-color support, even as an export option.

Try the “Indexed PNG” node before a Write node, and change the Colors: option to "2’. That should do the trick.

Also - make sure the “Keep original type” is set for the Convert to: option.

I’m afraid that doesn’t work. I’ll start at the end: “Keep original type” doesn’t matter. The original image is a grayscale TIFF, and “keeping it original” turns it into a PNG nonetheless, since the previous step was “Indexed PNG”. But setting Convert to: TIFF works too, with identical result:

The result is an image with indexed colours, just as the node suggests. I should have emphasized the “for print” better, because here’s the problem: the indexed colour has no meaning for print and is treated like RGB black: it gets converted to CMYK during PDF export or RIP and ends as C:83%/M:73%/Y:62%/K:88% (in my test, depending on colour profile) – a bit (or actually pretty much) of everything. A 1-bit image for print (like Photoshop’s so-called “bitmap” images) should be 100% black only.

I think I’m following you here, and RB won’t be able to help you out right now. But I’ll consider it a feature request.

For the 1-bit image, a “bitmap” image is just raw data from Photoshop? Or are you saving it as a 1-bit TIFF or BMP?

“Bitmap” in Photoshop is a colour mode in itself; you’d have to go through Mode > Grayscale first to strip all the colours, then choose Mode > Bitmap (screenshots are in German, but you’ll get the idea) to strip everything else. In the next step you get prompted for how you want to reduce it from 256 shades of gray to black and white: by threshold, via rasterization or dithering. This does pretty much the same as a RIP does, which is why print-ready 1-bit images won’t be further rasterized during but just get passed through.

The file can then be saved in several formats, but TIFF for print and PNG for web use are the most common.

I’ll be looking forward to this feature. In the meantime, GraphicConverter will do the job, though not nearly as elegantly. Thanks!