[Clipart] Art Submissions

[Jonadab the Unsightly One]

Open Clip Art Library Feedback Form <noreply at openclipart.org> writes:

> I\222d like to contribute to your project, however, these graphics
> are all in transparent PNG format. Do you accept this format? 

The main problem with the PNG format is that it is a bitmapped format,
i.e., it does not preserve any information about the shapes or objects
in the image, only the colors of a grid of pixels.  As a result of
this limitation, the image is really only useable at its original
size, in pixels.  Even with sophisticated resizing algorithms such as
bicubic interpolation, the image loses quality each time it is
resized.

For clipart, this can be a problem, because the user will usually want
the image at a different size from the size at which it was originally
drawn.  (This is especially an issue when using clipart in a document
that is intended to be printed, since printers achieve a much higher
resolution on paper than computer monitors can generally do on the
screen -- so the image needs to be available at a much higher
resolution for print than it would ever be for use on a web page.)

We use PNG format for previews and thumbnails and such, but we keep
the originals in a vector format, specifically, SVG.

It is easy to convert a vector image to PNG format, but going the
other way is not possible in the general case, without redrawing.
There are automatic tracing tools that attempt to make a vector image
from a bitmapped one, but the conversion is anything but exact, often
results in rather large file sizes, and in many cases leaves a lot to
be desired.  With some images the result can be pretty decent, with
some manual tweaking of the process, but the technique is not of
sufficient generality and applicability as to be usable for an entire
collection.

-- 
Open Clip Art Library:  Drawing Together
http://www.openclipart.org/