theft of images

Rodger Whitlock
Tue, 14 Dec 2004 16:13:42 PST
On 13 Dec 04 at 10:53, Mary Sue Ittner wrote:

> Our list does not allow attachments, but we have created a wiki
> where members can upload their images so that anyone who wants to
> can go online to view them...

> The images remain the property of the photographer, but there is no
> way we can protect them from people saving them to their own
> computer. Occasionally someone who is surfing the net becomes aware
> that someone has copied the images and is now using them on a
> commercial site.

You can watermark the images so that it is impossible to eradicate a 
statement of ownership. I've experimented with PaintShopPro and found 
that the following technique works fairly well.

Create a new black and white image 1.5 times bigger than the image 
you want to protect. Color the entire image black. Use the text tool 
to place your warning text, in white, on the image. Repeat until the 
image is filled with lines of warning text. I found that Microsoft 
Sans Serif worked pretty well as a typeface for this purpose.

Rotate this image 45 degrees counterclockwise, then crop it to the 
size of the image you want to protect. Assign your warning-text image 
to the to-be-protected image as a mask. Adjust the gamma to, say, 

Because of the mask, the gamma will only be adjusted where the white 
lettering exists on the mask. This means the warning text becomes 
visible across the protected image in the form of slight variations 
in brightness and contrast. By astute choice of typeface, size, and 
gamma correction, you can watermark your pictures without obscuring 
the details of the image.

I doubt anyone would be able to easily undo such watermarking!

A suitable warning text might be "for exclusive use on the pbs 
wiki/copyright 2005 John Doe, Podunk, Indiana/do not reproduce" but 
you are free to write anything you want.

If someone asks permission and you decide to grant it, use a fresh 
copy of the picture and watermark it referring to the site for which 
you have given permission to use it on.

Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island

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