Image artifacts
On 10/24/07, Jarlath Reidy wrote:
I have a friend who uses images sent to him by clients to make
engravings on various materials. This is a start up business and he is
having some teething problems.
He has an issue where the boundary between the foreground and the
background isn't clear cut and the engraving looks smudged around the
edges.
I've attached a piece of the image which the client sent in jpg format.
Unfortunately, the typical client is not very computer savvy and asking
for .tiffs isn't possible.
Not sure if I understand the question, but I removed the artifacts in
the image in this manner:
1. Convert image to grayscale
2. Adjust Levels - moving the rightmost slider inwards will "clip" the
light-colored artifacts in the background. Moving the middle slider
to the right will "squash" the dark-colored artifacts in the
foreground.
3. Save as PNG (as JPEG will only re-introduce atrifacts
Optionally
4. Open inkscape and import the new PNG
5. Trace the bitmap and save as SVG
(steps 4-5 can be accomplished in GIMP by selecting the foreground
areas, creating a path from the selection and importing it).
Now he should have a definite foreground/backgound in the PNG and
possibly a SVG that can be scaled up or down without distortion or
added artifacts. I would guess that in whatever process he's using
for engraving, vector artwork would be preferable (at least that's
what 99% of our vendors want).
This method won't always work - esp. if the JPEG compression is very
high, or the image resolution very low. Sometimes you have to bite
the bullet and pull out the pen tool :)
Let me know if this helps, or if I missed the point completely...
Chris
