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PNG Export with Transparent Background not working


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Hi everyone,

 

I want to export a png with transparent background so I can import it in my CAD software.

I created a document  1000x1000 pixels. Used a  tree-brush to create said image with a shadow.

Next I click on export PNG and when I go and import it in my CAD software it just doesnt let me choose a Alpha channel. So I assume theres none exported.
 

I tried all solutions that have been posted on the forum but I cant seem to get it right.

 

I added the file and a screenshot of the import window.

Thanks in advance for your help.

Vectorworks2019_vcBBd2hTRJ.png

Tree.afphoto

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Welcome to the forums.
I’ve just exported a PNG from your afphoto file and it seems to have exported with transparency just fine (see attached image where it’s placed over an image).
Have you tried to place your own exported PNG into either another Photo document or some other software, other than your CAD software?

Annotation 2020-01-22 095209.png

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2 hours ago, Intuos said:

Next I click on export PNG and when I go and import it in my CAD software it just doesnt let me choose a Alpha channel. So I assume theres none exported.

Perhaps for some reason your CAD software does not recognize the alpha channel? Like @GarryP mentioned, when I export your file to PNG on my Mac it definitely has a transparency alpha channel, as the Mac "Get Info" panel shows:

1569517053_treeinfo.jpg.20c13b043190adb8116fe90f1ef722fa.jpg

All 3 1.10.8, & all 3 V2.4.1 Mac apps; 2020 iMac 27"; 3.8GHz i7, Radeon Pro 5700, 32GB RAM; macOS 10.15.7
Affinity Photo 
1.10.8; Affinity Designer 1.108; & all 3 V2 apps for iPad; 6th Generation iPad 32 GB; Apple Pencil; iPadOS 15.7

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Its super weird though. I exported the file as PSD and gave it to a buddy who uses the same software. He exported it from PSD to PNG and then it worked fine in the CAD software.

 

He can choose in export "color with alpha channel (32-bit)" so it seems to me that affinity photo doesnt export it like that?

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2 minutes ago, Intuos said:

He can choose in export "color with alpha channel (32-bit)" so it seems to me that affinity photo doesnt export it like that?

I am not sure what software you mean he was using but most likely "color with alpha channel (32-bit)" just means 8 bits in each of the four RGBA channels. That would be the default for an .afphoto file using the RGB/8 color format when an alpha transparency channel is present.

All 3 1.10.8, & all 3 V2.4.1 Mac apps; 2020 iMac 27"; 3.8GHz i7, Radeon Pro 5700, 32GB RAM; macOS 10.15.7
Affinity Photo 
1.10.8; Affinity Designer 1.108; & all 3 V2 apps for iPad; 6th Generation iPad 32 GB; Apple Pencil; iPadOS 15.7

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I talked to the helpdesk of the CAD software and they sent a  step by step guide to work around the issue. Sadly its tailored for photoshop and in german :D

The gist of it is is that I should create a Layer Mask from the transparency. That Photoshop treats transparency and alpha channels seprate. 

Will be difficult trying to follow the steps which is focused on photoshop and how they relate to affinity.

 

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PNG doesnt support any number of alphachannels like other formats. PNG says that the fourth channel in a file is only for transparency. If you open a png with transparency in photoshop it will be viewed as a single-layer image. its not a flat background. Alphachannels can encompase everything, while transparency has a specific channel relation. YOu can have multiple alphachannels but only use one channel for transparency. Photoshop treats transparancy and alpha channels seperately. The transparency in a existing PNG can be edited in photoshop by creataing a layermask from the transparency-data.

  1. Open the Palette Info
  2. click on Palette Options top right and choose  Paneloptions
  3. for second colour value pick the mode "opacity"
  4. click ok
  5. the infopanel will show the level of opacity at the postion of the mouse
  6. if you want to edit the layer transparency directly, you can create a layer mask thats based on the layer transparency.
  7. Choose the layer
  8. choose layer>layermask>from transparency
  9. A miniature of the layermask will be displayed,which is connected with the layer. 

Masks are saved in alphachannels. In the channel window you should see a Layer-0-Mask. Hide the color channels and make the Layer-0-Mask visible by clicking on the eye to see the mask.

Masks and chanels are greyscale images, thats why they can be edited with the normal tools. Black areas are protected, white areas can be edited.

 

Hope it makes sense. I translated it from german.

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One thing you can try is to use the export persona to export. I find this can give a different result sometimes.
For example I did a quick test where I added a mask in Photo to a layer, exported as PNG using the export option and it came into Photoshop as a white background with no transparency. However, if  switch to the export persona, then choose the layer with the mask and create a slice from it, then export the slice as a PNG, then bring that into Photoshop I see it with transparency.

If you need to make a mask for the transparent areas this can be done easily by using the Select > Alpha Range > Select Partially Transparent. Then invert this using Select > Invert Pixel Selection, then click on the Mask Layer icon on the bottom of the layers panel to apply this as a mask to your layer. This doesn't come into photoshop as an alpha channel though (you just get the transparency built into the original layer), so not sure if that's an achievable from Photo, as Photo doesn't use channels in quite the same way as Photoshop.

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