Anti-aliasing pre-multiplying with white?

[Herbert123]

I am preparing graphics for web export. Please check the example image:

Untitled.png

Left Photoline (fixed layer), right Photoshop.

I prefer Photoline's overall anti-aliasing better, since I feel Photoshop's version is too soft.
However, it seem Photoline pre-multiplies with white, and introduces a lighter orange instead of a darker red along the edges where the transition takes place between the red and black background.

It's caused me some headaches trying to prevent this behaviour in PL, but so far no luck. Does anyone have an idea how to solve this?

[Martin Huber]

I am preparing graphics for web export. Please check the example image:

Untitled.png

Left Photoline (fixed layer), right Photoshop.

I prefer Photoline's overall anti-aliasing better, since I feel Photoshop's version is too soft.
However, it seem Photoline pre-multiplies with white, and introduces a lighter orange instead of a darker red along the edges where the transition takes place between the red and black background.

PhotoLine doesn't premultiply with white. The lighter edge looks like some kind of sharpening.

It's caused me some headaches trying to prevent this behaviour in PL, but so far no luck. Does anyone have an idea how to solve this?

Do you have a PLD (before fixing the layer) to reproduce the problem?

Martin

[Herbert123]

Hi Martin,

since this is a client logo, I sent you a direct link. Thanks for your help!

[greenmorpher]

Yes, looks like edge sharpening.

But to be frank, what's the sweat on the net? Given the wide variety of viewing conditions, w3hyo will see it viewed at 72 dpi?

Cheers, geoff

[Herbert123]

No, I did not sharp the edges at all. Merely fixed the layer. It's not visible before fixing, afterwards it is.

[Hoogo]

Some algorithms for scaling can produce effects like sharpening, too. Is it vector or pixel-based?

[Martin Huber]

No, I did not sharp the edges at all. Merely fixed the layer. It's not visible before fixing, afterwards it is.

There is a problem with fixing layers. I will change this.

You can circumvent the problem by either
- scaling the layer manually with "Layer > Scale Layer"
or
- filling the red part of the image with red without modifying the transparency (I just used the paint tool with a large brush).

Martin

[Herbert123]

No, I did not sharp the edges at all. Merely fixed the layer. It's not visible before fixing, afterwards it is.

There is a problem with fixing layers. I will change this.

You can circumvent the problem by either
- scaling the layer manually with "Layer > Scale Layer"
or
- filling the red part of the image with red without modifying the transparency (I just used the paint tool with a large brush).

Martin

Unfortunately, with red letters and a black outline even scaling with "layer-->scale layer" the effect occurs, and looks quite bad. Even <ctrl><shift><C> causes these artefacts.

Too many letters and icons to fill with red - would take too much time.

For now I'm forced to finish the work in other software. Looking forward to a new version with this bug squashed!

Thank you for your hard work.

[Paul]

Hi,

perhaps replace the red color (with 100% tolerance) with the right kind of red (with 0% tolerance)? It works fine with me in your image.

- Paul

[Martin Huber]

Unfortunately, with red letters and a black outline even scaling with "layer-->scale layer" the effect occurs, and looks quite bad. Even <ctrl><shift><C> causes these artefacts.

If you have red text and a black outline, this behavior is intended and not a bug. When scaling the interpolations Bicubic, Lanczos and Lanczos8 do have a certain built-in sharpening (with increasing strength). Linear interpolation doesn't have this sharpening, but is more blurry.

For now I'm forced to finish the work in other software. Looking forward to a new version with this bug squashed!

I tried "other" software, too, and in my tests it showed the same sharpening.
If you think that it behaves differently, I would appreciate a sample document and intructions how to reproduce the results (via support@pl32.com).

Martin

[Hoogo]

It seems that we agree that it is an effect of the algorithm used for scaling.
Some more suggestions how to treat this at the moment:
-Looks as if the logo would be best in vector instead of pixel.
-If the layer is red on transparency, use a brush to fill it with new color (Martin suggested it)
-Use a curve, interpolation mode "line" and create a plateau to reduce all pixels that are too red to the desired red.
-Scale the layer using "Layer > scale layer", mode bilinear. Then create an adjustmend layer for sharpening and set its mode to "darken".

[Herbert123]

Okay, I'll do a bit more testing this week. Thank you for all the help.

[Herbert123]

Okay, so I found out that my workflow was botched. This issue can be avoided when:

- scaling down the vector version first, and then fix the layer
- use bi-linear to scale down the bitmap versions.

In this particular case lanczos completely destroys the quality, while bicubuc adds the lighter red rim.

So, no bug indeed - just expected behaviour I was not aware of. Learn something new every day!