Affinity eraser won't stay inside selection, blurs edges around erase section

[Samweow]

I'm trying to erase the color inside the selection, but the eraser is erasing the area outside the selection as well, without 100% opacity. I want to only erase the area in the selection, and I want to erase it 100%

[thomaso]

In case you mean the blury soft edge: It seems your selection have feather set > 0.

p.s.: If you want to delete all pixels inside a selection you don't need to use the brush but can press the delete key.

[Samweow]

@thomaso I just checked and feather is set to 0 on the rectangle select, but I was using the magic wand, and even if I just press delete, it still has that feather effect

[Samweow]

When I colour with a paint brush also I get that same effect

[thomaso]

I wouldn't expect a difference between Erase vs. Paint Brush, in this situation they get limited by the selection which seems to be a lot smaller than your brush stroke.

I suppose the black areas are 1 color only, if yes, how come the Magic Wand (Flood Select Tool) did select some tiny spots only? Or did these details have a very subtle different color (we possibly don't see in your GIF)? – What was set as Tolerance?

• This selection looks like a square rotated by 45 degree, right? By coincidence?
• Was the selection on grey / behind the brush dialog window also done with the Flood Select Tool, with the "add" to selection button pressed?
• Or was the selection done on another layer which is hidden in the screenshot?

Can you show your entire screen incl. Layer panel with the active Flood Select Tool selection + the tool selected?

Edited January 29, 2022 by thomaso

[Samweow]

@thomaso

I used the quick select tool on the layer below, and switch to the top layer, but that shouldn't matter, the point is area outside the selection is being deleted with ~50% transparency. I want only the area inside the selection deleted, and I want it deleted 100%



 

[walt.farrell]

I agree that it looks like your selections are feathered.

You haven't shown us how you're making the selection. Could you do a video of that part of your process, making sure the Context Toolbar is visible?

[NotMyFault]

To check this out, create a mask from the selection. Then put the mask into solo/isolation mode (alt-click on layer thumb in layer stack). You will see partially selected pixels, meaning gray instead of pure black or white.

Alternatively, use the info panel, use a RGB probe, and look what the A value says while hovering over the selection area. The move tool should be active, to avoid getting confused by the preview rendering of the erase brush.

 

[NotMyFault]

The feathered selection can be caused by many factors, e.g. brush opacity, hardness, feather settings, using refine, …

If you need a 100% sharp selection, use a mask, select basic brush, 100% opacity/fill/hardness, and paint in either full black or full white. Inspect the result with info panel. Then select>Selection from Layer to convert into selection. This way you can be 100% sure and double-check.

[thomaso]

The reason for this feathered selection behaviour is quite likely in edits done to the gray layer. In your full screenshot the blocky, pixelated area at the right indicate that this layer has been upscaled at any stage of this document. Could be done by resize dragging or by altering the initial document resolution of this layer – both can influence this layer resolution in an undoable way, e.g. if rasterization gets applied, too.

In this clip both layers are/were Pixel layers at any time. The top layer is a copy of the lower layer, while the top layer has been downscaled + rasterized + upscaled.
• First compare the different selections (visible in red mask mode) occurring in the apparently quite similar layers : the scaled layer (top) results in different selection than the layer below.
• Then compare what happens if the document resolution gets reduced (here to 10% to make it more obvious): the formerly scaled layer is a lot more affected, and so the different selections get more visible.

[Old Bruce]

11 hours ago, Samweow said:

I used the quick select tool on the layer below, and switch to the top layer,

 I am curious about what those two layers are. What do they look like.

[Samweow]

@walt.farrell

 

[Samweow]

@thomaso I don't understand why that should matter, I feel like once I have the selection, where I got it from shouldn't matter and the selection should be an independent thing

[thomaso]

5 hours ago, Samweow said:

I feel like once I have the selection, where I got it from shouldn't matter and the selection should be an independent thing

That's true once you got the selection. But in your case it seems that the greyish layer you use to create the selection is the culprit for your blurred selection. Note in your last video the pixelation in the grey at 45% zoom level.

[walt.farrell]

@Samweow: Thanks for the video. It shows something I don't understand.

First, you're working on an Image layer, not a Pixel layer, so I'm surprised that the selection works at all. But the surprising thing to me is that with only a 1% tolerance that you're getting s selection of both black and gray. That should, I think, need a far higher tolerance. But perhaps it's because you have that Image layer. What happens if you Rasterize it first?

In any case, since you're doing a Flood Select, and using a non-zero tolerance, I think you will essentially have some feathering occurring, and as we've mentioned feathering can cause the problems you're seeing.kk

[thomaso]

2 hours ago, walt.farrell said:

First, you're working on an Image layer, not a Pixel layer, so I'm surprised that the selection works at all. But the surprising thing to me is that with only a 1% tolerance that you're getting s selection of both black and gray.

Walt, what makes you think that a pixel selection with the flood select tool would not work on an pixel image layer?

In the OP's screens I see the pixel selection of the gray image layer, appearing in front of / above all layers, so the black text layer just seems to be included in the selection.

Note, the OP has the Source set to "Current layer". Here's if the pixel-text layer is selected for the same flood selection position / tolerance but not contiguous:

Edited February 7, 2022 by thomaso

[walt.farrell]

45 minutes ago, thomaso said:

what makes you think that a pixel selection with the flood select tool would not work on an pixel image layer?

First, it's either a Pixel layer, or an Image layer. There is no "pixel image" layer.

The reason I'm surprised at it working is that the individual pixels of an Image layer aren't directly usable. But on the other hand, a pixel selection really isn't part of any layer, so maybe that doesn't make any difference.

Re: Contiguous: Thanks; I couldn't see that part of the Context Toolbar clearly enough. Your image makes it clearer.

Tolerance > 0 (as shown by the OP) would still give a feathering effect, I believe.

[thomaso]

18 minutes ago, walt.farrell said:

First, it's either a Pixel layer, or an Image layer. There is no "pixel image" layer.

An image layer appears to contain pixels only. It seems if a placed resource contains vector its layer type is not named "image" but "Embedded / Linked document" instead.

According to the help, a placed pixel image will remain a placed pixel image. Some call this instaed raster or bitmap image, while for others the term bitmap refers to 1 bit images only. That's why it requires a raster (pixel, bitmap) image layer of type "(Pixel)" to be enabled to get converted into a layer of type "(image)". So the term "image" has various meanings, as we all know from the image we or someone else personally have, whereas image as layer type appears to be used in Affinity only, though in an Affiniyt document also are images, regardless of their layer types.

Quote

 

Image layers retain all of the data from the original image, which remains intact when the document is exported.

An image layer has a container which retains the placed image's original colour space, resolution and physical dimensions (when placed at native resolution).

 

[kaffeeundsalz]

11 hours ago, Samweow said:

I don't understand why that should matter, I feel like once I have the selection, where I got it from shouldn't matter and the selection should be an independent thing

On 1/29/2022 at 5:17 AM, Samweow said:

the point is area outside the selection is being deleted with ~50% transparency. I want only the area inside the selection deleted, and I want it deleted 100%
 

I think the confusion here comes from your assumption that the marching ants, i.e. the moving dotted line in your image, are an accurate visual representation of your selection. They're not. Pixels can be selected, not selected – and also partially selected, which means their selection involves some degree of transparency. But Affinity Photo will only show marching ants for areas where the selection has >50 percent opacity.

That's why in your example it seems that the Eraser brush doesn't respect the limits of your selection. In reality, your selection area is simply larger than the marching ants suggest because it contains pixel that are selected with <=50 percent opacity.

To get an accurate view of your selection, use the Quick Mask feature by pressing Q or do what @NotMyFault recommends in this post. You need a different selection to achieve what you want.

 

 

[thomaso]

2 hours ago, kaffeeundsalz said:

I think the confusion here comes from your assumption that the marching ants, i.e. the moving dotted line in your image, are an accurate visual representation of your selection. They're not. Pixels can be selected, not selected – and also partially selected,

I think the confusion comes from… the fact that the selection is blurred even though the selection tolerance has been set to 0 or 1%. With a rather homogeneous looking grey area within the selection, a blurred selection is not to be expected.

As I noted above, this can happen with down- + upscaled layers / reduced + increased resolution, resulting in an obviously pixelated image with visible squares, larger than the document pixels but/and apparently not as homogenous as they look.

[JimmyJack]

@Samweow you've (greatly) changed the size of the layer to be sampled yes? Rasterize it and resample. 
(resizing the layer to be erased can also be a problem, but the selection itself looks "rounded" so it's the selection layer in this case.)
It's just another incarnation of the same old antialiasing issue that comes up over and over and over and over and over again.
In Affinity it's best to get into the habit of rasterizing after every single pixel manipulation. Otherwise you'll miss something and something will, eventually, get blurry and then you're screwed. You might not notice it the first time, but it's there and then problems can compound quickly.

Oh, and on the topic while we're here. The Tolerance setting on the FST has absolutely nothing to do with edge selection "fuzziness" or antialiasing. 1% or 90% it is always a hard edged selection. The fact that there is no antialias tick box for this tool, imho, is just baffling.
(And please, no-one say "oh, just use refine or blur the selection". It is absolutely not the same thing. It may do the trick on an amorphous selection but it's multiple fiddly steps when a tick box will (and should) do. And on other selections those options are no solution at all. If a feather is needed, then fine, use feather, but it's not the same.)

edit: I think @thomaso and I are saying the same thing.

 

[Samweow]

@JimmyJack

Thanks, that did it