Rasterize without antialiasing

[Milos Micatek]

Hi.

I am dealing with some specific item. I am creating the lettering using Pen Tool in Affinity Photo. The task is to create letter as curve and then turn it to pixel layer with crisp / sharp edges = no antialiasing. There is antialiasing around the curve edges but I found the solution  here from  @MEB to get aliased object by adjusting the Coverage Map. It works for vector object (curve) but when I rasterize the object to pixel the anti-aliasing is back. 

Is there a possibility to keep sharp edge after rasterizing? If not is there some elegant way how to make those edges sharp quickly?

 

[JimmyJack]

50 minutes ago, Milos Micatek said:

Is there a possibility to keep sharp edge after rasterizing? If not is there some elegant way how to make those edges sharp quickly

There may be, but I'll give an option for the "if not..." part.

Probably a bunch of ways, so I'll just kick off the melee () with:
With the rasterized layer selected go to Select dropdown > Alpha Range >Partially Transparent. Hit delete.

[Milos Micatek]

@JimmyJack Thanks a lot, it helps! If you have more of these "if not..." advices just throw them to me!

[lepr]

.

[drakecaiman]

Is this still the best way to do this? I tried to replicate this using the "Alpha" option in the "Select Sampled Colour…" panel. While it seems to select the parts I'd expect, it seems that some pixels are "partially selected" and are still affected though they are outside the boundary, as with this GIF.

[lepr]

@drakecaiman: set the coverage map for the vector object as shown in Milos' screen shot at the start of this thread, press cmd+g to enclose the object in a Group and then rasterise the Group.

[drakecaiman]

Perfect. Thanks!

[drakecaiman]

K, think I spoke too soon. Tried it again today and I still get pixels filling in outside of the given selection. I think I've found a workaround, but I had a few questions:

1. Is this behavior normal? Are the pixels outside the selection border "partially-selected" or the result of anti-aliasing the selected pixels? Is there a way to tell when his will happen?
2. I've managed for now to just invert selection and delete the extra pixels, but it takes a few strokes of the "Delete" key to clear it as it only partially deletes the pixel. What's controlling it complete or partial deletes pixels?

[lepr]

1 hour ago, drakecaiman said:

K, think I spoke too soon. Tried it again today and I still get pixels filling in outside of the given selection. I think I've found a workaround, but I had a few questions:

1. Is this behavior normal? Are the pixels outside the selection border "partially-selected" or the result of anti-aliasing the selected pixels? Is there a way to tell when his will happen?
2. I've managed for now to just invert selection and delete the extra pixels, but it takes a few strokes of the "Delete" key to clear it as it only partially deletes the pixel. What's controlling it complete or partial deletes pixels?

 

I don't know why rasterising the group is not producing an aliased pure black result. Please post the file (or another with same problem) at the stage immediately after setting the aliasing coverage map on the vector object.

[drakecaiman]

K, feel kind of stupid, but I just realized that the technique in the original post was done in Affinity Photo, not Designer. Did this in a trial version of Photo and worked without problem. Is this possible to do solely in Designer, or is Photo required?

[lepr]

33 minutes ago, drakecaiman said:

K, feel kind of stupid, but I just realized that the technique in the original post was done in Affinity Photo, not Designer. Did this in a trial version of Photo and worked without problem. Is this possible to do solely in Designer, or is Photo required?

The method I said to use works for me in Photo, Designer and Publisher. There's a better chance of solving this if you post the file I asked for.

[drakecaiman]

Just checking to make sure that wasn't the cause. Here's the file:

Raster Test.afdesign

[lepr]

5 hours ago, drakecaiman said:

Just checking to make sure that wasn't the cause. Here's the file:

Raster Test.afdesign 19.58 kB · 2 downloads

Thanks. The problem is the stroke alignment is "Inside". Despite the fill being empty, the coverage map is failing to affect the outside edge of an inside-aligned stroke or the inside edge of an outside-aligned stroke. However, you can do Expand Stroke (it has been much improved recently) to get the necessary aliasing when you don't want to use a centre-aligned stroke. Don't forget to have the result of the expansion in a Group and then rasterise the Group.

By the way, you get a preview of what rasterising will produce by switching the view mode to "Pixels"

[lacerto]

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[lepr]

34 minutes ago, Lagarto said:

c) Right click the ellipse layer and choose Rasterize. You should get a pixel layer that matches the preview.

No, you must rasterise the group that contains the ellipse.

35 minutes ago, Lagarto said:

Aliasing a non-center aligned stroke would probably require visiting the Pixel Persona and filling (at least part of) the antialiased pixels with black.

No, Pixel Persona is not necessary; I explained in the post immediately before yours that you simply use Expand Stroke before rasterising the group.

[lacerto]

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