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| author | Robin Watts <Robin.Watts@artifex.com> | 2022-01-20 18:19:24 +0000 |
|---|---|---|
| committer | Robin Watts <Robin.Watts@artifex.com> | 2022-01-20 18:22:17 +0000 |
| commit | 5fe77c896b08504dda008353129ca0df1e4a1a09 (patch) | |
| tree | 6717348ab54833da21395060053c9d9c3a01df47 /doc | |
| parent | 052d0f0bda2c7b5edffc75f16b2ea07514cd9977 (diff) | |
| download | ghostpdl-5fe77c896b08504dda008353129ca0df1e4a1a09.tar.gz | |
Add png16malpha device.
This is a clone of the pngalpha device, with antialiasing disabled
by default. People should use this, together with the DownScaleFactor
parameter to acheive antialiasing without the nasty effects given
in some cases by GraphicsAlphaBits.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/Devices.htm | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/doc/Devices.htm b/doc/Devices.htm index 2bc6cedab..8bcc1b9b2 100644 --- a/doc/Devices.htm +++ b/doc/Devices.htm @@ -223,15 +223,17 @@ black-and-white for special needs. The <code>pngmonod</code> device is also a black-and-white device, but the output is formed from an internal 8 bit grayscale rendering which is then error diffused and converted down to 1bpp.</p> -<p>The <code>pngalpha</code> device is 32-bit RGBA color with transparency +<p>The <code>png16malpha</code> and <code>pngalpha</code> devices are 32-bit RGBA color with transparency indicating pixel coverage. The background is transparent unless it has been explicitly filled. PDF 1.4 transparent files do not -give a transparent background with this device. Text and graphics -anti-aliasing are enabled by default.</p> +give a transparent background with this device. The devices differ, in that the <code>pngalpha</code> device +enables Text and graphics anti-aliasing by default. We now recommend that people use the <code>png16malpha</code> +device in preference, and achieve any required antialiasing via the <code>DownScaleFactor</code> parameter, +as this gives better results in many cases.</p> <h4>Options</h4> -<p>The <code>pngmonod</code>, <code>png16m</code>, <code>pnggray</code> and +<p>The <code>pngmonod</code>, <code>png16m</code>, <code>pnggray</code>, <code>png16malpha</code> and <code>pngalpha</code> devices all respond to the following:</p> <blockquote> @@ -267,12 +269,12 @@ behave as for 2.</dd> </dl> </blockquote> -<p>The <code>pngalpha</code> device responds to the following option:</p> +<p>The <code>png16malpha</code> and <code>pngalpha</code> devices respond to the following option:</p> <blockquote> <dl> <dt><code>-dBackgroundColor=</code><b><em>16#RRGGBB</em></b> (RGB color, default white = 16#ffffff)</dt> -<dd>For the <code>pngalpha</code> device only, +<dd>For the <code>png16malpha</code> and <code>pngalpha</code> devices only, set the suggested background color in the PNG bKGD chunk. When a program reading a PNG file does not support alpha transparency, the PNG library converts the image using |