Problem with soft brushes in 8-bit mode and "halo" gradients

[Frozen Death Knight]

I wanted to bring this issue some attention to the developers regarding soft brushes creating uneven gradients that are jagged between each value. The only way I have been able to find a fix to this is by switching the canvas to 16-bit mode (I work with RGB), but this also takes up a lot of resources, which can be quite taxing when I work on canvases at 6000 pixels or more. Here is an image comparing two gradients I painted with the exact same brush I use, but one was drawn while using 16-bit and the other with 8-bit.
 

This particular problem does not exist in Photoshop. In Photoshop you don't have to work with 16-bit canvases to create the smoother gradients like in the example image from Affinity Photo.

Then there is another issue with painting with soft brushes; the halos. While it isn't completely apparent in the above example image, when you softly apply your brush stroke to the canvas, the problem becomes way more apparent:



This, along with the 8-bit issues, make soft brush painting less than ideal at times. Using blurs and other techniques can help fixing some of the more serious problem areas in your paintings, but that shouldn't really be needed as far as I'm concerned.

I don't know what is causing this problem, but I do hope we can see a proper fix in at least the forseeable future. Fixing issues like these will go a long way in making me 100% recommend Affinity products to other people (still recommending it, but I always have to bring up little issues like these that can make it tougher to convince people).

[Chris B]

Hey Frozen Death Knight,

It looks like you've got Wet Edges enabled on the context toolbar.

With it disabled, I can see a halo (but I think is an optical illusion as it's picking R:0 G:0 B:0) whereas if I enable Wet Edges, it picks at R:63 G:63 B:63 with 0% Hardness. That would make this by design.

This might be why you're seeing the difference between 8-bit and 16-bt.

If you haven't got Wet Edges enabled, I would have to assume you're using your own document or monitor profile.

[Frozen Death Knight]

36 minutes ago, Chris B said:

Hey Frozen Death Knight,

It looks like you've got Wet Edges enabled on the context toolbar.

With it disabled, I can see a halo (but I think is an optical illusion as it's picking R:0 G:0 B:0) whereas if I enable Wet Edges, it picks at R:63 G:63 B:63 with 0% Hardness. That would make this by design.

This might be why you're seeing the difference between 8-bit and 16-bt.

If you haven't got Wet Edges enabled, I would have to assume you're using your own document or monitor profile. 

I am pretty sure I didn't have wet edges enabled when I did this test (still, I will have to double check once I get home from work). Been trying to solve it on my own, but to no avail.

The monitor I used was my Wacom Cintiq 13 inch HD screen with default settings, so that can be safely ruled out, since this problem is unique for Affinity Photo based on personal testing with other non-Affinity software on the same screen.

Document profile can possibly be the culprit, but I haven't really fiddled with it much and just use the standard one when creating a new document. What settings did you use when testing?

[Chris B]

12 minutes ago, Frozen Death Knight said:

What settings did you use when testing?

Nothing else in Affinity.

I did check Photoshop and that is also displaying the halo that we can see in Affinity,  however the effect in your screenshot is much more prominent than in mine 

[Frozen Death Knight]

On 3/8/2019 at 11:49 AM, Chris B said:

Nothing else in Affinity.

I did check Photoshop and that is also displaying the halo that we can see in Affinity,  however the effect in your screenshot is much more prominent than in mine 

Okay! That screenshot of yours in AP looks better than what I can get on my home desktop. Maybe I should post an actual file so you can check if there are any issues with how I set up the document or if it is a monitor issue on my end? I don't have it right now, but once I get home I will post it.

[Chris B]

56 minutes ago, Frozen Death Knight said:

Maybe I should post an actual file so you can check if there are any issues with how I set up the document

Yes, please—that would be great  

[Frozen Death Knight]

All right, will be back later today with the file!

[Frozen Death Knight]

@Chris B Hey, I'm back with a file!  Halo Soft Brush Artifacts.afphoto

I double checked if I had wet edges active, and it wasn't activated in the original screenshot. Here's some additional info about the file, my hardware, and AP settings if it is of any help:

- The ICC profile used was sRGB IEC61966-2.1 and an RGB/8 canvas.
- I run Windows 10 64-bit with an Nvidia Geforce GTX 980 graphics card, 32 GB DDR3 RAM, and an Intel Core i7-4770K 3.50GHz CPU.
- My monitor/tablet is a Wacom Cintiq 13" HD with standard monitor settings.
- The brush used was a standard soft brush in the Basic folder in the Brushes panel, with Accumulation Jitter set to Pressure at 100% (as mentioned earlier, no wet edges activated).

Hope this helps! ^^

 

[Chris B]

Hey Frozen Death Knight,

Thanks for the extra info and file.

It looks like this is due to dithering—or a lack thereof. We don't apply dithering to the brush whereas some other apps do.

I'm currently discussing this with dev so I'll update you when I can.

[Frozen Death Knight]

3 hours ago, Chris B said:

Hey Frozen Death Knight,

Thanks for the extra info and file.

It looks like this is due to dithering—or a lack thereof. We don't apply dithering to the brush whereas some other apps do.

I'm currently discussing this with dev so I'll update you when I can.

Okay, thanks for the info! I am looking forward to your reply about that then.

[lepr]

.

[Alfred]

4 minutes ago, >|< said:

If dithering is added to brushes, please make sure it is only optional so that it isn't forced on us when we don''t want it.

Seconded, although we don't mind it being forced on us when we do want it!

[keypix]

I am seeing this problem too!  

I have tweaked the brush settings to get it as good as possible but it's still not as smooth as photoshop.

I have noticed that the 8 bit photoshop brush is not smooth but has a random granular texture, you will need to zoom in around 1000% to see the difference.

Hope there is a fix asap!

[Frozen Death Knight]

@Chris B Hey again! It's been a bit more than month now since last we spoke, so I wanted to contact you again to see if you had any more information to share about the issue we discussed. Did you and the developer come to some sort of conclusion? Is this issue going to be hard to fix before the official 1.7 release, and if so, within what estimated time frame can we expect it to arrive? Thanks!

[Chris B]

On 4/19/2019 at 2:39 PM, Frozen Death Knight said:

@Chris B Hey again! It's been a bit more than month now since last we spoke, so I wanted to contact you again to see if you had any more information to share about the issue we discussed. Did you and the developer come to some sort of conclusion? Is this issue going to be hard to fix before the official 1.7 release, and if so, within what estimated time frame can we expect it to arrive? Thanks!

This was initially raised as a bug but was closed as by design (which is makes sense because we don't currently dither). However we then asked if this is something we could maybe look at adding but so far it has gone unanswered. 

I don't know how likely this is to make it into 1.7 as the developers are now heavily focusing on ironing out bugs and ensuring no regressions make it into the newer beta releases at the moment. I'll update you with any new info. 

[DylanGG]

+1

Can we get an update regarding this, @Chris B?

[Alfred]

On 4/23/2019 at 9:25 AM, Chris B said:

we don't currently dither

 

20 minutes ago, DylanGG said:

Can we get an update regarding this, @Chris B?

I think they must be dithering!

[DylanGG]

 I'm asking if we can get an update for this to be implemented, I don't understand your response whatsoever.

[NotMyFault]

out of curiosity,

I tried to manually add a live diffuse filter (the dither for poor Affinity users) and this doesn’t look great. The main issue with soft brushes and RGB/8 and grey color is that you have only a very limited number of steps which naturally introduces banding. And other than banding of gradients which is easily to resolve by dithering, it is more complex with soft brushes as the „onion rings“ width changes from brush stroke center to brush stroke edge. This would require increasing strength of dither on the edge, probably introducing ugly results.

Another option would be sub-Pixel anti-aliasing (similar to font anti-aliasing), but this would give color artifacts.

If anybody could provide a sample file of the result of brush strokes from (a) Affinity and (b) other Apps, this would be great. 

If possible, use identical settings, and helper objects to get the brush stroke in the exact same positions.

brush:

• size 1024
• hardness 0
• color black

 

1. one stroke (one click)
2. two strokes (two clicks at same position), 
3. two brush strokes by individual clicks  (1/4 of brush width distance)
4. A brush stroke (line) over 2x brush width

 

[Chris B]

On 2/26/2022 at 2:53 PM, DylanGG said:

+1

Can we get an update regarding this, @Chris B?

I've just gone to look at the report and it has already been updated to reflect 1.9. I've added a comment as well. So far though, nothing has been done development-wise 

[Anthony Okon]

It's V2. I love it, but i think we still have the same issue (i guess) across all 3 programs. Will something be done about it?

switching to 16 and 32 shouldn't even have to happen.

Please guide me if i'm wrong.

thanks.

 

[Frozen Death Knight]

@Anthony Okon Work with 16-bit canvases at the bare minimum and export in 8-bit after. Performance wise Affinity deals with 16-bit and 32-bit pretty well. You can't really work with 8-bit canvases while brush gradients create such ugly halos and grains, so it's the only real solution until they add dithering to their brush engine.

The other "alternative" is to blur with filters or the Blur Tool afterwards, but really, that's just a ton of extra work for something that can be done by increasing the bit rate.

[Anthony Okon]

15 hours ago, Frozen Death Knight said:

@Anthony Okon Work with 16-bit canvases at the bare minimum and export in 8-bit after. Performance wise Affinity deals with 16-bit and 32-bit pretty well. You can't really work with 8-bit canvases while brush gradients create such ugly halos and grains, so it's the only real solution until they add dithering to their brush engine.

The other "alternative" is to blur with filters or the Blur Tool afterwards, but really, that's just a ton of extra work for something that can be done by increasing the bit rate.

Ok. Thank you for the advice. I appreciate it.