Removed background on object... but outline effect not working?

[cassiopoia]

I removed the background on this pixel object, but then when I go to add an outline effect, it is outlining things I can't see...What is going on? Did I not remove the background properly? 

I'm on a macbook pro, 12.0.1 Monterey. Just updated my Affinity Designer to latest version. 

[carl123]

7 hours ago, cassiopoia said:

What is going on? Did I not remove the background properly? 

That could explain what you are seeing

If you missed erasing just a single pixel the outline FX would be generated for that pixel as well

Use the Erase Brush Tool with a hard brush selected and go over those areas again and see if the outline disappears

If not, uploading the document would be the quickest way to get a more definitive answer.

 

[NotMyFault]

There are probably some pixels left with residual transparency.

There are difficult to spot, but you can add a levels adjustment, select alpha channel, and move white level to 1%. Then all partial transparency gets fully opaque  

or simply use Carls advice and erase again where the layer fx shows the issue.

[firstdefence]

It really depends on what the background was originally and also the method you used to remove that background; I would suspect the Erase Tool (E) in which case you have missed areas of the background. Try creating a contrasting background i.e if the background was white, fill a pixel layer with dark colour to highlight any areas missed.

Use the Selection Brush Tool (W) to select the oysters , invert the selection and press delete. 

[thomaso]

4 hours ago, NotMyFault said:

There are probably some pixels left with residual transparency.

There are difficult to spot,

This reminds me to the Alpha Selection option, expecting it makes any transparency visible by a running ants selection marquee.

Now I wonder why this auto-selection doesn't work here for 5 % opacity / 95 % transparency? Is there any tolerance I can set for this command? Also a bucket fill set to 0 % tolerance appears to ignore the brush stroke of 5 % opacity. – What am I misunderstanding, misexpecting or misusing with "partially transparent" here?

[NotMyFault]

27 minutes ago, thomaso said:

Now I wonder why this auto-selection doesn't work here for 5 % opacity / 95 % transparency?

It works, but the marching ants will bot show them.

The ants show only the 50% transparency “height line”. In case you have only pixels with transparency below that level, they get selected, but no ants show up. Edit: while correct in general (selection from layer), this does not apply for select partial transparent pixels. The resulting selection is digital, either 100% or 0%, and not linearly to their opacity value. I have to check on Mac which alpha values define the inclusion criteria, i assume 1/255 to 254/255.

To check, use channels panel (selection thumbnail), or activate quick mask which allows other options to inspect the actual selection.

[walt.farrell]

11 minutes ago, thomaso said:

What am I misunderstanding, misexpecting or misusing with "partially transparent" here?

It seems to have selected almost your entire canvas in that initial selection, perhaps because with your brush characteristics there are very few fully opaque pixels.

Then, too, there's the 50% threshold for the marching ants, as @NotMyFault mentioned.

[thomaso]

43 minutes ago, NotMyFault said:

It works, but the marching ants will bot show them.

The ants show only the 50% transparency “height line”.

41 minutes ago, walt.farrell said:

there are very few fully opaque pixels.

Then, too, there's the 50% threshold for the marching ants

Thanks, the 50 % limit is good to know! Do I understand right it concerns the ants visibility only, not the actual selection?

I still wonder what "partially" means for this alpha selection next to "fully transparent" and "no transparency = fully opaque". The bucket fill set to 0 % tolerance fills the 100 % transparent area as expected but includes the 95 % transparent area, too. I would expect it to exclude any opacity if set to 0 % tolerance. – No?

Doesn't the bucket fill here demonstrate that the "partially transparent" selection includes "fully transparent" AND even most opaque areas, excluding only a tiny area within the darker stroke?

It's confusing to me in particular because the Outline Effect is well aware of the 5 % opaque / 95 % transparent area – which is commented to result in the unwanted stroke of the OP's concern.

[NotMyFault]

Its all fairly  simple complex:

• outline will be painted within the given radius around every pixel which is not fully transparent
• outline will cover only pixels which are fully transparent (except next point)
• Edit: if you make an outline around a partially transparent pixel, you will see a kind of anti-aliasing effect.  It is difficult to describe in words, just test it on your own. Add a 4px wide layer fx outline in red, applied to a rectangle with 2px wide stroke (in blue) (assuming perfect pixel alignment) Now adjust the stroke opacity between 0 and 100. You can see the stroke kind of breathing. At 100%, the outline will be exactly 4px. At lower opacity, the 4th px of the outline will reduce its opacity according to the stroke opacity, bur the stroke pixel itself seems to stay at 100% opacity. 
• There are potential bugs with outline and semi transparent fill. It really starts to get confusing if you dig deeper, nothing really adds, unable to understand what is intended (and why) and what is a bug (and why).

you can use a 100% selection of a 50% transparent pixel, or vice versa. This could lead to different results.

Actually, you can stack at least 3-4 levels of transparency:

• color alpha
• Nested or inherent mask alpha (fill layer)
• layer alpha
• anti-aliasing alpha 
• selection alpha

understanding how these different alphas combine or act differently depending on context could be challenging.

 

outline and transparency.afphoto

[thomaso]

6 hours ago, walt.farrell said:

there are very few fully opaque pixels

4 hours ago, NotMyFault said:

you can use a 100% selection of a 50% transparent pixel, or vice versa. This could lead to different results.

Maybe I was unclear because of being confused. Aside this topics Outline Effect I first want to understand what a "partially transparency" in fact includes and excludes. It appears, either the Alpha Selection menu command or the bucket fill tool treats fully transparency as a subset of partially transparency (which feels really strange):

I would expect that "partially" would neither select fully opaque nor fully transparent pixels. Aside the visual ants marquee limitations I would then expect such a selection of "partially transparency" would not get filled by the bucket tool in the "fully transparent" areas. Or, as in my video above, if I click on a 100 % transparent spot with tolerance = 0 then the bucket would exclude pixels which are above 0 or between 1 – 100 % transparency, and thus would either NOT fill the two brush strokes but their surrounding only or would fill the brush strokes but NOT the 100 % transparent area.

Can you follow my doubts and concerns?

[walt.farrell]

@thomaso: Here is one example, using Select > Alpha Range > Partially Transparent. All of the pixel layers are the same color, with varying opacity specifications in the Color panel as noted. The brush is a basic brush at 100% hardness/flow/opacity, with Wet Edges off. The selection picked up everything (including the transparent background) except the 100% opacity patch.

Here is an Alpha Range > Fully Transparent selection, which excluded all the pixel patches, and included only the transparent background:

 

Here is an Alpha Range > Opaque selection. It includes only the 100% patch:

 

When you test using brushes you need to use a basic brush with all the hardness/flow/opacity at 100% and Wet Edges off, or you'll get transparency within the brush stroke that is harder to judge. Just play with the color transparency, or make separate pixel layers and play with the layer transparency. This helps make things easier to understand.

Regarding the Flood Fill Tool, here is what I get if I set it to 0% tolerance and click on a fully transparent part of the canvas:

Everything is filled except for any of the pixel areas I've painted on.

[thomaso]

13 minutes ago, walt.farrell said:

Here is one example, using Select > Alpha Range > Partially Transparent. (...)
The selection picked up everything (including the transparent background) except the 100% opacity patch.

Walt, thanks for your tests + screenshots! – Unfortunately (or luckily?) your first shot seems to demonstrate + confirm my confusion: 100 % transparent is a subset of partially transparent?

To me "partially transparent" would mean everything different than 0 % and 100 % transparency, and thus exclude both 100 % opacity + 100 % transparency. But it appears to exclude 0 % transparency (= your top most 100 % opaque stroke) while it does not exclude the opposite but selects the 100 % transparent background area. – How come? Especially since there exists a separate option to select 100 % transparency.

Do I misunderstand "partially"?

I would answer "no" to each of this 3 questions. – How about you or other users?

[NotMyFault]

2 hours ago, thomaso said:

Maybe I was unclear because of being confused. Aside this topics Outline Effect I first want to understand what a "partially transparency" in fact includes and excludes. It appears, either the Alpha Selection menu command or the bucket fill tool treats fully transparency as a subset of partially transparency (which feels really strange):

I would expect that "partially" would neither select fully opaque nor fully transparent pixels. Aside the visual ants marquee limitations I would then expect such a selection of "partially transparency" would not get filled by the bucket tool in the "fully transparent" areas. Or, as in my video above, if I click on a 100 % transparent spot with tolerance = 0 then the bucket would exclude pixels which are above 0 or between 1 – 100 % transparency, and thus would either NOT fill the two brush strokes but their surrounding only or would fill the brush strokes but NOT the 100 % transparent area.

Can you follow my doubts and concerns?

I agree that "Select Partial Transparent pixels" selects fully transparent pixels, seems illogical.

My file contains a test pixel layer, the first 20 pixels om theft are fully transparent, and get included (I rate this as bug).

 

 

Select by alpha bug.afphoto

[Old Bruce]

I can answer yes to all of your three questions, I feel that answering no means none of the circle is black, none of the star is white and the glass is utterly dry.

[walt.farrell]

Is something which is fully transparent also partially transparent?

In some ways that feels similar to whether "pick a number between 1 and 10" includes the endpoints. 

Or whether, given a collection of 2 objects, how many subsets you can form. That is, can a subset have no members, or can it have all the members.

But given three choices (transparent, opaque, partially transparent) it would seem reasonable to expect that they are exclusive, and that partially transparent should exclude items that satisfy (Edit:) either of the other two choices.

 

[R C-R]

53 minutes ago, walt.farrell said:

But given three choices (transparent, opaque, partially transparent) it would seem reasonable to expect that they are exclusive, and that partially transparent should exclude items that satisfy both the other two choices.

I think you mean it should exclude either of the other two choices?

Anyway, I can see how "partially transparent" could be interpreted as meaning anything that is neither 100% transparent nor 100% opaque, but also as anything that is not fully opaque.

[cassiopoia]

Wow thank you for this discussion folks! Carl's answer to erase pixels helped me solve this issue. The rest of the discussion is excellent learning material for me to digest!

[thomaso]

Interesting, I didn't expect to get 3 different views on this, in particular because it is a menu command which should have a clearly defined function.

@Old Bruce seems to see partially transparent as a condition for full transparent. For @walt.farrell and @R C-R partially transparent seems to be ambiguous, respectively can be both: a subset or an exclusion of full transparent. And @NotMyFault rates it as a bug.

In my understanding I could answer the sample picture with "yes" only if the question would be "Is the object at least partially ..."

3 hours ago, NotMyFault said:

I agree that "Select Partial Transparent pixels" selects fully transparent pixels, seems illogical.

My file contains a test pixel layer, the first 20 pixels om theft are fully transparent, and get included (I rate this as bug).

3 hours ago, walt.farrell said:

But given three choices (transparent, opaque, partially transparent) it would seem reasonable to expect that they are exclusive, and that partially transparent should exclude items that satisfy both the other two choices.

The three different views on this are still confusing to me of course, so I tried another approach to find the Affinity understanding of "partially transparent". Back to this topic's issue: It occurred already in the forum here and there, mainly with unexpected white or light areas around placed images with apparently isolated content. This made me try to select via the Flood Select Tool. And I run into another unexpected result:

It appears if I flood-select a 100% transparent area with tolerance from 0 % to 99 % the selection is always the same and selects 100% transparency only:

This makes me wonder how can I select all pixels with a transparency above 0 % and below 100 % transparency?

If I invert this above selection and subtract with 0 % tolerance the 100 % opaque area it results again unexpected to me: it subtracts also some partially transparent area next to the opaque stroke (see the blue arrow):

This seems to mean that I misunderstand the tolerance setting, too. Wouldn't 0 tolerance select only kind of identical pixels (colour or opacity) ?

Walt, what do you get in your Flood Select sample if you subtract the 100 % opaque stroke with 0 tolerance and 'Contiguos' unticked?

[walt.farrell]

8 hours ago, thomaso said:

It appears if I flood-select a 100% transparent area with tolerance from 0 % to 99 % the selection is always the same and selects 100% transparency only:

That matches what I showed above for 0% Flood Selection. I didn't think to try higher values.

But it makes sense to me that the tolerance wouldn't matter, as Flood Selection is based solely on the color components of the pixels. Transparency doesn't matter. Here are several red brush strokes in Photo. All are the same red (RGB values), but with different opacity values. I clicked Flood Select once in the fully opaque stroke, with tolerance set to 0%, and all the strokes were selected:

8 hours ago, thomaso said:

This makes me wonder how can I select all pixels with a transparency above 0 % and below 100 % transparency?

Select > Alpha Range > Opaque, then invert the selection.

8 hours ago, thomaso said:

Walt, what do you get in your Flood Select sample if you subtract the 100 % opaque stroke with 0 tolerance and 'Contiguos' unticked?

Again, Flood Select is based solely on the RGB values, not the transparency, so Tolerance shouldn't matter if the only difference is in the opacity.