On Tue, 27 Nov 2007 22:18:28 -0700, Norm DePlume wrote:

On Tue, 27 Nov 2007 22:22:59 -0500, Andrew Kalten
In addition, IMG_6297 copy.jpg contained 30,172 bytes of extraneous
data, compared with warbirdz_12327.jpg, which contained only 79 such
bytes, as determined by comparing file sizes before and after processing
with jStrip v3.3. And, actually, there are any number of Windows
compatible graphics programs that can accomplish this task easily, but
no, they do not ship with Windows. As to whether the difference is
beyond perception, I am not prepared to state such a conclusion so
definitively.

I had no time to do a statistical analysis of the difference file,
but a quick glance using a histogram tool showed that the average
difference in luminosity was about 3-4 (out of a maximum of 255).
Since the threshold for the detection of luminosity differences
by the human eye is about one percent, this difference will just
barely exceed that level. Looking at the difference image, a vague
area of greyness is just barely discernible.

But this difference is at the lower end of the luminosity scale.
In the actual image, the differences occur in much brighter areas
where the eye is less sensitive to change and such differences are
very apt to go completely unnoticed.

So unless you are very deliberately and very intently looking for
some small difference, the images will be identical.

AK