re-visiting jpg quality

[JRR]

There has been at least one lengthy discussion re the quality of jpg one should use in the images for PTE.

There is, of course, no one right answer as it is a very subjective issue. Amongst other things it depends on how the AV will be presented (computer screen vs projector), how large an .exe file you are prepared to work with, etc etc

There is a very good demonstration of the differences between the quality settings:

here in UTUBE

You will see the differences are quite subtle.

[Conflow]

There has been at least one lengthy discussion re the quality of jpg one should use in the images for PTE.

There is, of course, no one right answer as it is a very subjective issue. Amongst other things it depends on how the AV will be presented (computer screen vs projector), how large an .exe file you are prepared to work with, etc etc

There is a very good demonstration of the differences between the quality settings:

here in UTUBE

You will see the differences are quite subtle.

Hi Jim,

I had a look at that 'UTube Demonstration' but for the life of me I can't see what the Author of that

Production is trying to achieve vis-avis:- JPeg Saving Qualities !!

1)

It is well known that JPeg Images are "lossy" Images which deteriorate with multiple 'Saves'.

2)

And the same can be said about the 'Save' quality settings from Zero ~ 100% where 95% is about the

best quality before the Image resolves into a 'Bitmap-Image' at the 100% level.

3)

Even if he took 'multiple-copies' of the (original) Image and saved these (original) Copies at different

quality settings of course there will be differences as the Image resolves from the Black-level (0%) to

the Bitmap-level (100%) and prior to that exercise the (original) Copies themselves will have been

compromised by the action of making copies of the (original) Photograph in the first instance.

4)

A simple 11 Bar Grey-Scale Test or Color-Bar Test would have shown the differences immediately.

I simply can not understand what the Guy is trying to achieve excepting in giving us a demomstration

of the obvious which is known to anyone who uses an Image-Editor whether Photoshop or otherwise.

Sorry, but it's gone over my head...

Brian.(Conflow)

[davegee]

Tom's JPEGs are a good illustration of what can happen. Photoshop's "Save For The Web" gives the same sort of result.

However it must be added that viewing at 400% is not the "norm".

I have always used 100% when looking for artifacts but I have to admit that artifacts which appear to have gone when viewing at 100% can still be seen if the view is increased to 400%.

So where do you stop?

Erring on the side of caution I don't go below quality 8 when doing a "Save As".

DG