atw: Re: black and white





Erisa.
This is a test that for one reason or another (too many to quote here),
that imaging software cannot do for you.
Allan, Michael, Daryl and others all came up with the same things that I
have considered.

You require a rigorous, repeatable and reliable method to achieve this.

Some of the reasons:
Greyscale images are interpreted using various types of algorithm, from
both ends of the colour spectrum (black or white), and you never know who
is using which type of algorithm, unless they tell you (and the writers
don't know because developers aren't dumb enough to explain it in simple
terms). That means your images used for percentage variation measurement
are always going to be different.

Scanning images is fraught with variation, from the beginning (scanner
manufacturers scanning software; driver colour interpreting software).
Importing images into software packages is also fraught with variations,
Scan an image into Photoshop using the incorporated get image functions and
see the choices you are presented with).

Image qualities (from the rgb to cmyk to colour gamut choices, to the
possible selections of colour inking proof choices etc etc) are open to
each users and each packages own interpretation, as are the video driving
systems versus the printer driving systems. Consequently, Photoshop, Paint,
Corel and all the other imaging software produce different colour
variation, outputs etc etc.

(As a test, go and create an image in Photoshop, illustrator, Corel draw,
Corel photo paint, and another in MS Word. Use the rgb scale colours in
each software package with the same numbers for colouring your image.
Import the outside images into Word, and print the file with two different
colour inkjet printers (or use a colour inkjet and a laser printer). Note
the variation. Now go and import the group of images into Photoshop and
compare the greyscale histograms.
Conclusion: They WILL ALL BE DIFFERENT.

What you are asking for (or being asked for) is impossible.
If you want the name of an academic at Macquarie University to help you, I
can do that. He is a specialist in that field.

Warren Lewington.

**************************************************
To post a message to austechwriter, send the message to 
austechwriter@xxxxxxxxxxxxxx

To subscribe to austechwriter, send a message to 
austechwriter-request@xxxxxxxxxxxxx with "subscribe" in the Subject field.

To unsubscribe, send a message to austechwriter-request@xxxxxxxxxxxxx with 
"unsubscribe" in the Subject field.

To search the austechwriter archives, go to 
www.freelists.org/archives/austechwriter

To contact the list administrator, send a message to 
austechwriter-admins@xxxxxxxxxxxxx
**************************************************

Other related posts: