Transparent background is turned black when pasted

[minespatch]

I thought fandom wikia was doing something funny with transparent images recently  but when I copy pasted a gif image into paintdotnet, the transparency turned into a black background. I think it has to do with the program itself but maybe I'm wrong.

[ancient]

I've recently had this same problem happening to me. For years, I could drag a png out of the browser and paste it in no issue, but only tonight have I now had the problem of dragging it in making all the supposed to be transparent areas black.

 

Copying and pasting retains the transparency, but at the same token, that's a few extra steps as opposed to the easy drag that was able to happen before. Especially when I never even really touched my settings, the fact that this all of a sudden has changed is a bit irksome. The fact that it only happened to me tonight, and the same happened to you in the same time frame, tells me that there's probably something up with the program right now.

[null54]

4 hours ago, ancient said:

I've recently had this same problem happening to me. For years, I could drag a png out of the browser and paste it in no issue, but only tonight have I now had the problem of dragging it in making all the supposed to be transparent areas black.

 

Dragging and dropping requires the browser to save the image to a temporary file before Paint.NET can load it.

 

It appears that Firefox is saving the image as a BMP file instead of a PNG.

Dragging and dropping does not work with Chrome or IE, it appears that they use clipboard formats that Paint.NET does not support.

[ancient]

 

6 hours ago, null54 said:

Dragging and dropping requires the browser to save the image to a temporary file before Paint.NET can load it. 

 

It appears that Firefox is saving the image as a BMP file instead of a PNG. 

 

Well that's weird, because again, I've done it for years without issue

[Rick Brewster]

1 hour ago, ancient said:

Well that's weird, because again, I've done it for years without issue

 

Then Firefox must've changed how they do this. I'd report the bug to them.

[HyReZ]

I been experiencing a similar effect, but it doesn't appear to involve Paint.NET.

When using FireFox or Opera to collect Internet images, I create a folder on the Windows 10 desktop that I drag & drop my Internet images that have transparent backgrounds (PNG, WEBP). When I look at the thumbnails for those images some (not all) will have a black background within that folder, while others will have a transparent background. I thinking that it may have something to with updates to Windows 10.

Edited February 9, 2019 by HyReZ
to add more nfo / correcting errors

[Reptillian]

It's a unsolved Windows bug. This happen with other softwares too, not just PDN. Linux clipboard works just fine and Mac as well.

[Rick Brewster]

It's not even an unsolved Windows bug -- it's an unsolveable Windows design flaw.

 

The clipboard can take data in many formats, including bitmaps, sometimes called DIBs (Device Independent Bitmap). One of the properties for a bitmap is the pixel format, e.g. 8-bit indexed, 24-bit RGB, or of course 32-bit RGBA. The flaw is that the DIB format does not include any way to specify the format of the alpha channel: is it premultiplied, or straight? Some apps put content on there as premultiplied, others as straight, and apps like Paint.NET kinda just have to guess or infer. If there's also a PNG on the clipboard then it's unambiguous and things work fine, but DIBs are just flawed and will never work 100% of the time.

 

As @null54 pointed out, Firefox needs to put a PNG on the clipboard, or a link to a file containing a PNG.

 

Also, as a corollary, DIB is the same binary format used by BMP files. This is why Paint.NET does not support 32-bit BMPs with alpha: because there's no information to tell it how to interpret the alpha channel.