Displaying a PNG with alpha transparency?

[terrypin]

In PSP 8 I made a circular white clock face with black numerals on green background. I then saved it as a PNG, specifying the green as the transparent colour and specifying alpha channel.



It worked OK when viewed in my video editor, i.e. the green was transparent. But on opening it 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. Is this also the case in less ancient versions? What about other image editors - do they all have this weakness?

--
Terry, East Grinstead, UK

[hartpaul]

Just tested it in my PSP8 X2 and X4 and works OK with no problems Clock face shows against checkerboard (transparency)

[terrypin]

Thanks for testing it. That reinforces my vague recollection that I used to get a chequer board too. Wonder what's going on. Presumably there's no user setting influencing this? I'll try a PC reboot shortly.

--------------------

Edit: No change after PC reboot. And I also re-ran the 8.01 Update patch. My version is 8.10, presumably same as yours that shows checkerboard?

Any more suggestions please?

--
Terry, East Grinstead, UK

[hartpaul]

Oh just saw the difference. I had the Single colour transparency button tagged and not the Alpha Channel. I think they are exclusive as you can only set one button of the three.

[terrypin]

Our posts must have crossed - just seen yours immediately after sending mine.

That makes no difference here. I can save with either option. But on opening the new PNG it still has a white background.

--
Terry, East Grinstead, UK

[terrypin]

Not for the first time on this forum, I was in the final stages of posting more information when, after returning from an XP folder, I found my post had vanished!

I'll reconstruct it quickly. This illustration should be self explanatory.



When I created a new version of a transparent white circle on a grey background, that once again displayed the circle as white.

So frustrating.

--
Terry, East Grinstead, UK

[hartpaul]

You are now confusing me by introducing a grey background. Lets get back to the original white clock face, black letters, green background.
I gather you want a png where the white clock face and black letters (clockface) is on a transparent packground.

Try this:
1 from original clockface on green background - Layers palette Right click the layer and Promote background layer.
2. Use magic wand tool, Mode Add, Match Mode RGB, Tolerance 80, Anti Alias on - select the green and hit the delete key to get your clock face on a transparent background.
3. Selections > None. Save as png. Do not use the Options > Optimiser. (my default was Non interlaced and Optimised palette).
When I drag and drop that into my PSP 8 workspace it shows exactly as I saved it with the clockface on a transparent background.
Do you get this.?

Note: on a Tolerance of less than 80 in Step 2, I still had a considerable green fringe.

[terrypin]

Thanks for sticking with me on this. But now you're confusing me a bit too!

My problem and the issue we've been discussing isn't how to make these transparent PNGs. It's why my PSP8 doesn't display them properly when subsequently re-opened, yet yours does. That grey one just happened to be one I found I'd made a couple of years ago. None that I make now display properly.

But I'll duplicate your steps when I get back to my PC.

It might also be worth trying a file from elsewhere, as the evidence indicates the cause lies in the creation stage. For example, can you upload that one of yours?


Terry, East Grinstead, UK

[hartpaul]

Here is link to the image I produced in PSP8
http://i477.photobucket.com/albums/rr14 ... 4a954e.png
and the image:

[terrypin]

Just going out for the day so will check again this evening later. But after following your steps (but see exception below) no checkerboard. Nor dragging in your downloaded file. Yet I made one very early this morning in IrfanView and that DID have correct checkerboard.

Re not using optimizer. Are you sure? I get the usual message that layers will be merged if I do that. Either way, same result.

Friday 5 July 2013, 09:28, UK time

--
Terry, East Grinstead, UK

[LindaSue]

I don't get the checkerboard for Terry's clock face image in any of my versions of PSP. But, when I manually removed the white background and re-saved it as a PNG image, I now get the checkerboard when I reopen it. I don't ever use the area color match option though. I always keep my PNG optimizer set to "Existing image or layer transparency" and create my images on a transparent background to begin with. Was there a reason for putting the clock on a green background rather than on a transparent background?

[LindaSue]

Re not using optimizer. Are you sure? I get the usual message that layers will be merged if I do that. Either way, same result.

The layers will be "merged" but not "flattened". The message is just letting you know that you've got more than one layer and PNGs can only have one. If your image does have another layer that's filled with a color that you don't want to display in the final image, you can just turn off the visibility of that layer before saving the file and it won't show when you reopen the file.

[terrypin]

Thanks LindaSue, appreciate your help on this. It's puzzling, although sort of reassuring, that you too don't see checkerboard on my file, unlike hartpaul who does.

I'll get back into this methodically tomorrow. But I'm having trouble grasping what is wrong with my assumptions or logic in the simple steps below:

1. Open a new raster image with any solid colour.
2. Use the PNG optimizer to specify that as the single colour to be made transparent.
3. Save it as PNG.
4. Drag that back into PSP and expect to see it entirely checkerboard.

(I'm not suggesting that's a 'good' way to make transparent images, just a very simple one that logically should work!)

Do either of you have IrfanView? As mentioned up-thread I made a partially transparent image with that (albeit unsatisfactory as it apparently doesn't allow any tolerance setting) and it displayed with checkerboard in PSP 8.

--
Terry, East Grinstead, UK

[hartpaul]

Hi Terry, just followed your steps in PSP8.00 on XP Home SP3 and got the checkerboard pattern with no problems.
In Irfanview double clicking that image and it shows as black rather than green which is how I believe Irfanview shows transparency in a png file (Irfanview 4.30).

Re "getting message layers will be merged" is your layers palette showing more than one layer?

Edit: Used Single color transparency and Alpha Channel transparency with no difference. Always get the green changing to transparent.
Here are my settings.
1. the file I started with - 1 layer
2. Optimiser settings
3. The saved image reloaded.



Edit 2:
Just repeated process in PSP8, X2, X3, X4, and X5 all with the same result. No merging layers warning when saving (as there is only one layer) , reloaded image s all showed transparency as in 3 on diagram.

[LindaSue]

Just in case this might be part of the issue, how do you have your file format preferences set? This is how mine is set for PNG: