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markw

Incorrect Pixel Dimensions from Designer Export Persona: Current MAS & Beta1.7

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Hello all,
I noticed yesterday that both the current MAS and Beta versions of Affinity Designer will under some conditions output files of half the expected pixel dimensions than intended when using the Export persona.
This only seams to happen if the documents dpi is set to 144 or 192.

The attached test document is 34x60px (and contains 1 free chilli!)
Set the document's dpi to 144 or 192.
In the Export Persona, I set slice output options for x1 and x2 png.
The x1 output is 17x30px : expected size 34x60px
The x2 output is 34x60px : expected size 68x120px

Export Size Test v1.6MAS.afdesign


macOS 10.14.6  15" Macbook Pro, 2017  |  4 Core i7 3.1GHz CPU  |  Radeon Pro 555 2GB GPU + Integrated Intel HD Graphics 630 1.536GB  |  16GB RAM  |  Wacom Intuos4 M

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I'm not sure about your experience with a dpi of 192.

But for the 144dpi case, I think you're seeing an effect of Affinity's support of Mac Retina displays.

Most (that is, non-Retina) displays are 72dpi. When you have a dpi of 144 I think that Affinity assumes you're designing for a Retina display. At that point x1 produces a non-Retina result (1/2 the size of the design, assuming it will be used for a non-Retina purpose) and x2 produces the actual size.

(Exact details only approximate in this post; I don't have a Retina display and haven't actually played with this myself.)


-- Walt

Windows 10 Home, version 1903 (18362.356), 16GB memory, Intel Core i7-6700K @ 4.00Gz, GeForce GTX 970
Affinity Photo 1.7.3.481 and 1.8.0.486 Beta   / Affinity Designer 1.7.3.481 and 1.8.0.486 Beta  / Affinity Publisher 1.7.3.481 and 1.8.0.502 Beta

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I wonder that too for a bit but then why dose Exporting from File > Export , which is basically @ x1, give image sizes of, in this example, 34x60px at 144 and 192 dpi?

As I say I'm only encountering this discrepancy in the Export Persona.


macOS 10.14.6  15" Macbook Pro, 2017  |  4 Core i7 3.1GHz CPU  |  Radeon Pro 555 2GB GPU + Integrated Intel HD Graphics 630 1.536GB  |  16GB RAM  |  Wacom Intuos4 M

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Hi both,

Sorry for the delayed reply

The slice export size ( 1x, 2x, 3x, etc) is linked with your document DPI. 1x is considered 72, and so on.

If your document DPI is set to 72, you will have the following for a 100px square

  • .5x - 50 x 50
  • 1x - 100 x 100
  • 2x - 200 x 200
  • 3x - 300 x 300

@144 dpi, you're basically working on 2x. So you will have:

  • .5x - 25 x 25
  • 1x - 50 x 50
  • 2x - 100 x 100
  • 3x - 150 x 150

@216 dpi, you're working on 3x

  • .5x - 16 x 16
  • 1x - 33 x 33
  • 2x - 66 x 66
  • 3x - 100 x 100

I hope this helps. 

Thanks,

Gabe. 

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Thank’s for the reply Gabriel. Appreciated:)
I confess though that I’m still confused:S by three things;
1: How dose Designer know what I want to use the output file for?
If I’ve made my image size X x Ypx that’s what I need and there is nothing in the documentation warning the user that they might get something smaller.
2: Why do I only see this downsizing of pixels with the Document preset dpi options of 144dpi and 192dpi?
3: Why dose File > Export work as I would expect with no automatic downsizing of an image at any Document dpi?

 


macOS 10.14.6  15" Macbook Pro, 2017  |  4 Core i7 3.1GHz CPU  |  Radeon Pro 555 2GB GPU + Integrated Intel HD Graphics 630 1.536GB  |  16GB RAM  |  Wacom Intuos4 M

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25 minutes ago, markw said:

3: Why dose File > Export work as I would expect with no automatic downsizing of an image at any Document dpi?

Because (I believe) the multi-size export capability based on document DPI is a function implemented only in the Export Persona.

The Export Persona and File > Export have different purposes and different capabilities.


-- Walt

Windows 10 Home, version 1903 (18362.356), 16GB memory, Intel Core i7-6700K @ 4.00Gz, GeForce GTX 970
Affinity Photo 1.7.3.481 and 1.8.0.486 Beta   / Affinity Designer 1.7.3.481 and 1.8.0.486 Beta  / Affinity Publisher 1.7.3.481 and 1.8.0.502 Beta

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I am trying to understand @Gabe answer.

So ... in Affinity, 1x is always = screen DPI  ? ... and the slice panel tries to export the image inch size at xx screen resolution ?
So the formula is: Export pixels = xx * (Screen DPI / DocumentDPI) * pixels ?  

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Not exactly, but close.

  • If your document DPI si a multiple of 72, 1x is always 72.
  • If your document DPI is not a multiple of 72, the document DPI will be treated as 1x.

So, for example, if your document DPI is 150, a 100px square @ 1x will result in a 100px square. If you have the same 100px square on a 144dpi document, 1x will result in a 50 px square. 

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