white line around picture

[globso]

im wondering about these white lines that occurs on my pictures. i have made a a3-canvas and imported a picture witch i have scaled down to make it fit the a3. 
but these white lines keep showing up. it sems by random, since as you can si on the two top pictures at zoom 56,7% the line is clearly visible but if i zoom to 70% as the picture below its gone. 
 i can paint it away, as seen on the two bottom pictures at the bottom, but i rather not have them at all. why are these edge lines occuring? 

 

[GarryP]

An A3 document will be 3507.874×4960.63 pixels (in portrait) – see attached image.
Because of this, the software is trying to handle the 0.874-width / 0.63-height pixels in its own way, and doing its best, but there will always be some kind of discrepancy with non-integer pixel dimensions.
Also, non-integer zoom levels - such as 56.7% - will also sometimes cause odd effects; how does the software display a fraction of a pixel in whole pixels?

Make sure your image is slightly larger than the canvas – in whole pixels – and you should be okay.
You may still see the lines but you shouldn’t need to worry about them.

[R C-R]

5 hours ago, GarryP said:

An A3 document will be 3507.874×4960.63 pixels (in portrait) – see attached image.

That is what the New Document window displays for the A3 preset if you switch Document Units to Pixels, but once you click the Create button, the document's actual pixel dimensions will be 3507 x 4960 px -- the fractional pixel part is ignored.

The fractions show up in the mm display of the dimensions & will be 296.926 mm by 419.947 mm.

[Old Bruce]

5 hours ago, R C-R said:

That is what the New Document window displays for the A3 preset if you switch Document Units to Pixels, but once you click the Create button, the document's actual pixel dimensions will be 3507 x 4960 px -- the fractional pixel part is ignored.

Not so in my experience. If I change (only) from mm to pixels in the new document dialog, my new document has fractional pixels and is still the original mm size.

[R C-R]

33 minutes ago, Old Bruce said:

Not so in my experience. If I change (only) from mm to pixels in the new document dialog, my new document has fractional pixels and is still the original mm size.

Are you testing with Affinity Photo or Affinity Designer? I was testing with AP because from the OP's screenshots the tools seem to be those from AP.

But when I tested just now in AD, I get the same thing you do.

So I guess the two apps do not work the same in this respect?

[GarryP]

I created a 10×10 cm document (300DPI) in Designer, Photo and Publisher, then changed the UOM to Pixels and tried to resize the document and found that the document/spread height/width was 1181.102 pixels in each – see attached images. (This was on Windows 10.)

More experimentation may be required but the point I was trying to get across is that unless the document dimensions are integer values in both pixels and non-pixels then the software will need to ‘cope’ with fractional pixels in some way, and that ‘coping’ may not produce what the user expected.

[lacerto]

Obsolete.

[globso]

i use affinity photo. and it seams that if i check the box "transperant background" the lines dissapear some what, not compleatly but it looks better. i really dont understand why "transperant background" isnt standard as the default setting anyway. 

[lacerto]

Obsolete.

[R C-R]

9 hours ago, Lagarto said:

The macOS and Windows versions of Photo behave differently in that the macOS version does not show the fractional pixels in the Transform panel, or when resizing the document, while the Windows version does.

??? Fractional pixels show in the Mac versions if Preferences > User Interface > Decimal Places for Unit Types is set to show them. For example:

 

The fractions also show when resizing by dragging selection box handles, when dragging across the W or H field names with the pointer, etc.

9 hours ago, Lagarto said:

Both versions, however, behave similarly in that respect that while the document is created with fractional dimensions, the canvas is in practise handled limiting it to integer dimensions rounded down to the nearest integer

I can't say how it works in Windows or for anybody else, but for me AD does not round any of the "A" presets to the nearest integer pixel dimensions but AP does. For example, for the A4 preset in AD, on the left is the print preset & on the right is the AD resize doc dialog, clearly showing that the document has fractional dimensions:

 

For completeness, the same A4 windows in AP:

 

[lacerto]

Obsolete.

 

[R C-R]

1 hour ago, Lagarto said:

Yes, the fractional pixels show (on macOS, too) when the document is created but not when it is resized.

I was not talking about resizing anything, just the difference in how the two apps display the presets, for example how the A4 preset shows fractional pixels in the AD resize document dialog before anything is resized. 

[lacerto]

Obsolete.

[R C-R]

3 hours ago, Lagarto said:

For me Affinity Photo behaves identically with Affinity Designer so it shows the fractional pixels when creating a document:

Yes, for creating documents that is what my screenshots show. The difference is in AD, to resize I open the File > Document Setup window, where (as in my second screenshot) the dimensions initially still show the fractions. In AP, to resize I open the Document > Resize Document window, where (as in my forth screenshot) no fractions are shown.

[lacerto]

Obsolete.

[Dan C]

13 hours ago, R C-R said:

I can't say how it works in Windows or for anybody else, but for me AD does not round any of the "A" presets to the nearest integer pixel dimensions but AP does. For example, for the A4 preset in AD, on the left is the print preset & on the right is the AD resize doc dialog, clearly showing that the document has fractional dimensions:

 

For completeness, the same A4 windows in AP:

 

Thanks for the report! I've logged this with our developers now, as I can see these decimal values should certainly show