OT: Displaying transparency in image editors

terrypin wrote on 7/4/2013, 2:07 AM

I'd be interested to know if others' image editors display areas of transparency in any unique way please?

In mine, PaintShop Pro 8 (PSP8), I made an image on a green background. I then saved it as a PNG, specifying the green as the alpha channel transparent colour.

It behaved as expected when viewed in my video editor, i.e. the green was transparent. But on opening it again in PSP 8 I expected to see it displayed with the familiar chequer board background, yet it was a solid white.

So among many other PNGs it's impossible to tell that it does have a transparent area. Do all image editors have this limitation? I'd have thought it would be a desirable feature to distinguish transparency?

Also for thumbnails in Explorer folders too.

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Terry, East Grinstead, UK

Comments

johnebaker wrote on 7/4/2013, 12:59 PM

Hi Terry

No problem here with PSP X5. - I used the the Export, png optimiser and specified the transparency there.

This may seem a stuid question however - why did you specify a green background and then make it transparent?

I start with a transparent background and add a colour raster layer above if I need to see more clearly what I am doing, and save as a pspimage, when I am ready to save as png I hide the colour layer with the eye icon and save as a png.

John

terrypin wrote on 7/4/2013, 3:37 PM

Thanks for checking that John. I had a similar reply in the Corel PSP Forum from someone who tried it in several versions including PSP 8. It's so frustrating! I've tried dozens of examples and none show their transparent areas as checkerboard, always pure white. I tried both vector and raster circles and various colours.

Nothing significant about that green one. It made an easy test and a good screenshot. I'll try your method if I can break the habit of always starting with plain white or black!

And to add further to the mystery, I found several old files that do show checkerboard when opened. Here's an example:

Based on the descriptive filename it was a large white circle on a grey background, with AR = 16:9 from a couple of years ago when I was experimenting with masks. But after creating another like that, it does not display the checkerboard when reloaded into PSP8.

Yet if I create a new file with transparent background at the outset, that does show correctly.

I've rebooted my PC with no change. So frustrating!

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Terry, East Grinstead, UK

johnebaker wrote on 7/4/2013, 4:20 PM

Hi Terry

I think it is starting with a coloured background that is causing the problem.

You can do this however you must start a new layer before adding any objects, text or coloured shapes and 'turn off' the background before you export / save as png'

John

terrypin wrote on 7/6/2013, 5:28 AM

I think it is starting with a coloured background that is causing the problem.

Hi John,

Turned out to be more obscure than that! Got the answer over in the PSP8 Forum. It's down to this setting in PSP 8 File > Preferences > File Format Preferences > PNG

My setting was enabled. As soon as I unchecked it all the transparent PNGs happily revealed their checkerboards.

A residual issue (you know I hate unsolved puzzles) is understanding exactly why that setting has this effect?

Hope you have a great weekend. Mine was at risk as I anticipated being stuck on the PC during tomorrow's Murray Wimbledon final. Sad, eh?

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All I need to complete the feel good factor (apart from a Murray win) is to get my perfect clock working!

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Terry, East Grinstead, UK

johnebaker wrote on 7/6/2013, 4:07 PM

Hi tTerry

That setting makes does not quite make sense!!!

The Alpha channel is a fourth 'colour' channel ie RGB + alpha is stored in the png image, why telling PSP to load/save display the alpha channel the background colour causes a solid solid instead of transparent is a bit of mystery.

In a png image a pixel can be set to a RGB combination (ie colour) or transparent as happens when the option you discovered is not checked or my method is used. When the option is checked then the pixel is still set to its original colour and the alpha channel now holds the transparency information.

Yet PSP appears to be ignoring this alpha channel.

Interestingly this is the same option setting in PSP X5

John

terrypin wrote on 7/7/2013, 5:51 AM

Morning John,

Agreed, very strange. And adding to the puzzle, the PSP 8.10 user (same version as me) who suggested that setting change which sorted my problem cannot herself get checkerboard! She says:
"I'm using PSP 8.10. It was the final version of PSP8. It wasn't a patch or service pack. It was a completely new version with all of the previous patches included in it. Anyone who bought the CD version, and registered it, was sent a new CD in the mail when 8.10 was released. You had to uninstall your previous version of PSP8 before installing 8.10."

But I got to 8.10 via the '8.10 update patch', to 8.01 I think.

So IMO it points to a version and/or registry issue.

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You'll have to show us your airshow videos sometime!

I too may get back to some creative work soon, instead of technical puzzle solving.

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Terry, East Grinstead, UK