How to create precise halftones using Affinity Photo

[Dead Bat Designs]

Hello,

I am trying to migrate to Affinity Photo after years of using Photoshop. I do screen printing, and the one feature of Photoshop I absolutely cannot give up is the ability to convert a greyscale image into halftones with precision (basically, what options are given when you convert greyscale to bitmap in Photoshop). As Affinity does not seem to offer a "Bitmap" file format, I don't see how to do this? I have seen that there is a "Haltone effect layer", but this does not offer the options for precision that I need. Is there some way to do this in Affinity Photo?

Thank you.

[stokerg]

Hi @Dead Bat Designsand Welcome to the Forums,

I'm only aware of the Halftone Layer effect method.  We don't have the same options as we don't have the ability to create 1-bit Bitmap as PS does.  There are a few requests, one being here so hopefully we will see an improvement to the halftone side of things in a future build  

 

[Dead Bat Designs]

Thing is, you don't need to convert to a 1-bit bitmap file, just convert to a greyscale file that's either 100% black or 0% black with no shading in between. The main thing is some way to specify "45lpi elliptical dot" or something precise. It has been a feature in Photoshop *for at least 15 years*, so it's not some crazy new thing. I wonder if the issue is that the algorithms are covered by patents?

[walt.farrell]

31 minutes ago, Dead Bat Designs said:

just convert to a greyscale file that's either 100% black or 0% black with no shading in between.

You can manually convert to grayscale, in several ways, before applying the Halftone filter. And you can ensure the dots are 100% black or 100% white with a Threshold adjustment, if necessary.

33 minutes ago, Dead Bat Designs said:

The main thing is some way to specify "45lpi elliptical dot" or something precise.

Unfortunately, I'm not sure what that means. You can control the angle used for the screening in the Halftone filter, if that helps.

[Dead Bat Designs]

The halftone filter layer does not give the ability to specify lines per inch, and it has round dot option but not elliptical dot option. For screen printing, you need to create halftones at specific lpi, dot shape and angle to get proper results with different screen fabric mesh counts. Also, using the filer layer but then adding threshold afterward would create quite imprecise results. There are separate RIP software options that can apply halftones at the point of sending the file to the printer, but that adds further cost so lessens the value of switching to Affinity vs giving in and paying the Adobe monthly subscription, which I in no way want to do (I just had to finally retire my old MacBook which had old enough version of Mac OS X to keep running my old, paid for versions of Adobe software). Affinity seems like a great option, I want to support them but the lack of this one very old, simple feature is a glaring problem.

[iconoclast]

I support this suggestion. But in the meantime you could possibly give an older version of GIMP a try for this. Up to and including GIMP 2.8.22, it had a Halftone Filter that would possibly fit your needs (Lines per Inch...). Since 2.10... the new Halftone Filter of GIMP is unfortunately more like the one in Photo. GIMP also supports the Bitmap (*.bmp) format, and you can convert to 1 bit black and white (Indexed Colors).

Edit: There is also a Halftone Filter in the free G'MIC Plugin (category "Patterns"), but I don't think that it is what you're looking for.

[issicus]

I was able to get something equivalent to a phtoshop bitmap by using a live layer halftone filter and merging visible.  rasterizing the halftone in other ways resulted in anti-aliasing around the dots.    Now i'm looking for a way to change the halftone shape, i'm not sure how well 'round' will work.