Re: Graphics formats

[Dave Pawson <davep at dpawson dot co dot uk>]

On Mon, 2005-04-18 at 09:49 +0200, Justus Piater wrote:

> Here's what I think is the common wisdom:
> 
> 1. If your graphic data is in vector format:
> 
>    * Keep it in vector format for as long as possible during the
>      vector pipeline. I.e., never explicitly convert it to raster
>      format.
> 
>    1.1. If you are targeting print output:
> 
>         Since you'll probably be generating PDF or PS, you'll
>         typically convert your graphics to (vector-format) PDF or EPS.
> 
>    1.2. If you are targeting Web output:
> 
>         The most common formats are SVG and Flash.
Did you know that Adobe bought Macromedia?
> 
>         Since all vector-based Web graphics formats currently require
>         browser plugins (and in any case will continue to demand
>         sophisticated browsers), for maximum portability you will want
>         to offer an alternative raster image (inside an <object> tag,
>         for example). See 2.2.2 below for the recommended format.
> 
> 2. If your graphic data is in raster format:
> 
>    2.1. If you are targeting print output:
> 
>         Since you'll probably be generating PDF or PS, you'll
>         typically convert your graphics to (raster-format) PDF or EPS.

SVG =>eps. How please?

> 
>    2.2. If you are targeting Web output:
> 
>         2.2.1. If your data are composed of smooth transitions
>                (typically, this includes all photographs and almost
>                nothing else):
> 
>                Use a lossy format enabling a high compression rate at
>                almost no visible loss of quality (JPEG/JFIF).
> 
>         2.2.2. If your data contain discrete colors, drawings etc.
>                (this includes most non-photographic data, or
>                photographic data with line graphics overlaid):
> 
>                Use a lossless format. I highly recommend PNG 
My belief also. 


>                For discrete-color drawings, you get better compression
>                ratios than JPEG, at perfect quality, while JPEG
>                creates salient approximation artifacts.
Our print-floor people talk about colour separation. I don't understand
that. I guess it is making a  separate colour plate for one of 3 or 4
colour plates for printing. Is that right?
  I.e. not applicable to the people at home?


> 
>                There is almost no reason to use GIF anymore, as PNG is
>                much more versatile and often more efficient.
>                Exceptions are alpha-channel transparency for use with
>                Microsoft products (well supported by the open-source
>                community however) and animated raster graphics (MNG is
>                still not very widely supported).
> 
> 
> The essence: Don't throw away any information if you can avoid it.
Makes good sense.

> Note that PDF and PS/EPS can represent both raster and vector data.
(only if you know how to get from what you have to PDF|eps|ps)

> 
> There are open-source tools for essentially all conversions that arise
> in practice. The hardest are probably conversions to and from SVG. I
> wrote a couple of Java classes for converting SVG <-> EPS based on
> batik.  E-mail me if you're interested.

OK Justus. Unless the rest of the docbook community object, I'll play 
the loud-mouth know nothing. 

How do *you* get from SVG to eps? Please?

Of course everyone else knows how.....
  Don't you?

regards DaveP