The Purpose of image marking:

You may want to place marks on your image for two reasons.

1. First, to identify yourself. This will allow viewers of your image, even when the image has been copied from the web site, to find their way back for purchasing quality versions of your image.
   
   
2. Second, marking your image can discourage inappropriate reuse of your image on the web.

File Format and Compression Quality:

The file size and file format are the first line of defense in image protection. The size of your large image for web presentation should generally not exceed 400 pixels in the longest dimension. The format of your large image is JPEG. This format sacrifices image quality for smaller image sizes. Compression causes the file to throw out some image data. Enlarging the image or printing the image (something an image pirate might try) brings out these defects more clearly than the computer monitor.

The JPEG format offers a sliding scale of image quality, generally presented as 1-10 or 1-100. Image quality and file size are reduced as the number gets smaller. Choosing level 5 (or 50) will usually give you good visuals on a computer screen, but begin to look bad when printed. This should be your starting point for picking the right compression. Do not repeatedly open and edit a JPEG file, each time you save it the image is degraded. Plan to do this as the last thing in you image editing for web use.

Visual Marking:

Since we encourage visitors to use the visuals for project planning purposes (unless you state an image is not available for resale) it is likely they will get separated from the contact information on the web site. Visual watermarks can help your admirers find their way back to you as well as limit the use of your image. Visual marks are sometimes referred to a "scarring". This term is a harsh one that while true, turns off many people from using visual markings. As image creators we want the viewer do see and appreciate what we have created. We have to make a balance between applying marks for protection, and not obscuring the art to an annoying extent. Below is a sample with several mark types. It is recommended you use type one or two. The third type will be a duplication of information that is presented with your image on the site, so it is optional.

1. Transparent text with drop shadow will stand out on different backgrounds. Its main purpose is to allow the viewer to find you again. By placing a permanent address on the image you can change your contact data any time at the Science-Art.com or Medical-Art.com web site and customers can still find you.
   
   
2. A large transparent mark renders the image very difficult to reuse, but still allows the viewer to see the art. This one was created in PhotoShop 5.0 with the text tool and emboss effects. Any one color image can be used as a watermark. Place the image in a separate layer in PhotoShop and apply the emboss filter, then adjust the transparency of the layer and flatten the image.
   
   
3. A straight ahead copyright notice at the bottom of your image can be used alone or in conjunction with mark one or mark two. It is easily removed and offers little useful information for contact. But it does show ownership.

Hidden Marking:

Hidden marking does little to protect your images from blatant theft; file size, file compression, and visual marks are the best defense for that. There are two types of hidden marks:

-The first is not so much a mark as a file tag - the Info. box. The second is indeed a hidden mark.

Info Box:

PhotoShop and other image editing programs offer an "Info." dialog box where you can enter information, copyright, captions etc. If the image is reopened in a compatible image editor, the info. box can be checked for information.

Hidden Watermarks:

The most common brand of watermarking software is Digimarc, it comes with PhotoShop. You can also download the plug-ins from the Digimarc web site and use them with other software that accept PhotoShop Plug-ins.

To use Digimarc, you go to their web site and sign up for an ID number. This service now has an annual fee, even for the most basic account. You enter your contact information in their database and receive a Digimarc ID number, a PIN number to verify you are using the right ID number; and you pick a password so you can go back and edit your contact data at any time.

-Armed with these numbers you use the Embed Watermark plug-in to mark your image with a noise pattern that contains the ID number. This should be the last operation you do on your image before saving it for the web. Also it will only work on RGB images so the file format you will save is JPEG. The difficulty is the lossy nature of JPEG. It will also degrade the hidden watermark. The reader will show you the strength of the mark when you reopen you image file.

-When an image is opened in an image editor with the Read Watermark plug-in installed, the image window will show a symbol. Selecting the Read Watermark filter will pop up a window with a direct link to the Digimarc web site where the viewer can check your contact information.

-If you care to pay Digimarc some more money, they will cruise the web with their automated software looking for pirated copies of your image. They also offer a free stand alone watermark reading program.

For a more complete discussion of image protection on the web check this overview: http://gnsi.science-art.com/2000PT/posters/griswold/