png2pdf - A converter from PNG to PDF
=====================================

Usage:

png2pdf	-h
png2pdf --help

	shows this help text.

png2pdf -v
png2pdf --version

	shows version information

png2pdf -c <options>
png2pdf --configure <options>

	sets permanent options. See below for options you can set

png2pdf -C
png2pdf --show-configuration

	shows the current set of permanent options.

png2pdf -u
png2pdf --unconfigure

	removes the permanent options.

png2pdf -r <options>
png2pdf --reset <options>

	temporarily overrides the permanent options.

Options:
--------

-p <pdf-level>
--pdf <pdf-level>

	specifies the PDF level. Maybe 1.2, 1.3 or 1.4.

-n
--interpolation

	adds an entry to the image dictionary suggesting PDF viewers
	to show an interpolated image. This is usefull for stretched
	images (small images shown in a large screen area).

-m <background-rgb>
--mix-background <background-rgb>

	mixes against the background contained in the file's background
	chunk or against the specified background color if the file
	doesn't have a background chunk.

-s 
--mix-specified[=bool]

	sets the background specified in the -m option to have
	higher priority than the background from the file's background chunk.

-i
--image-mask[=bool]

	writes an image mask based on the PNG file's alpha channel
	if available.

-a
--transparency[=bool]

	writes transparency data based on the PNG file's alpha channel
	if available.

-l
--invert-levels[=bool]

	inverts the decision level for image mask creation. Normally
	only pixels having 0 opacity are masked out. This option
	masks all pixel having opacity in range 0...254.

-t
--alpha-transparency[=bool]

	treats the alpha channel data as transparency. By default the
	alpha channel is treated as opacity data.

-f
--file-time-check[=bool]

	When running on a directory we do it in make style. A new PDF
	file is created only for those PNG files which are newer
	than the appropriate PDFs.

Examples:
---------

png2pdf -c -p 1.4
	sets PDF format level to 1.4.

png2pdf -m 255,255,255 x.png x.pdf
	converts x.png to x.pdf. If x.png has a background chunk the color
	from that chunk is used for color mixing, otherwise we mix
	against a white background.

png2pdf -m 204,204,255 -s x.png x.pdf
	converts x.png to x.pdf mixing against a light blue background
	regardless whether or not there is a background chunk in the file.