Reducing presentation file size

[mdoyle]

I found a few somewhat relivant comments under FAQs, but none of them seem to fit my need. I need to know how PTE can be set-up to automatically create smaller .exe files. A similar software product automatically created a 24 MB file from 81 images and one 4+ minute long MP3 file. PTE created a 381.5 MB file from the same files and I cannot detect any difference in quality when I compare them. Any ideas or suggestions?

[MikeL117]

Hi

As far as I am aware PTE does not re-compress your original files which gives you the choice of how much of a trade off between quality and file size.

From your figures you look to be using uncompressed image files at SXGA resolution. This ia a lot of information for your poor computer to process (dragging the files off the CD or even hard disk is a slow process). If you were to save them as JPEG you should be able to get a good 10:1 compression before you see any significant degradation on screen for most images.

It would appear that the other software is automatically applying this level of JPEG compression which may be fine for most images but some you may want at higher quality.

The above are guesses. If you could get back with a little more details perhaps we could be more specific in guidance.

[Ken Cox]

mdoyle

give us the average size of the 81 images

are they

jpg

gif

or bmp

most members use jpg's +- 80 to 150 kb each

ken

[imfinewine]

Sure is something amiss. I just did a 116 side show with 10mins of music and an avge image size of 500k. It totalled 66meg.

Think Ken is right they can't be compressed at that size.

Dave

[denwell]

This is correct - you must decide what file sizes your images should be, and save/convert them to this size (usually 80-150k jpgs) before using them in PTE!

116 x 500k = 58MB + sound file =66MB

116 x 80k = 9.28MB + sound file = something much more manageable!!

Den (NE UK)

[DaveG]

Hi, I see a lot of members talking about file sizes of 80kb to 150kb.

I find that, no matter what compression method I use, and I have tried them all, I cannot get artefact free 1024x768 jpeg images at less than about 350kb.

Any comments?

DG.

[Ken Cox]

what program are you using to lower the size

I and a lot of other members have good luck using Irfanview -- i generally use a compression ratio of 80

% quality for jpgs

ken

[LumenLux]

I have come to most often use the "save for web" algorythum(?) of Adobe products.

[ronwil]

Dave

In my experience the final size in Kb depends on what work one might have done in photo editing, which I use a lot. My final image I size to 1024x768 (for a 4:3 ratio) and Save for Web at 80%. Of the 35 images I have just assembled into a sequence, apart from the title which is 579 Kb, the largest is 486 Kb and the smallest 153 Kb. I find no problem with that.

Ron [uK]

[MikeL117]

'Save for Web' in PhotoShop or ImageReady is excellent for compression as it gives you a clear indication of the amount of degradation caused by the JPEG compression. Select what you are happy with, but don't look for perfection or even look too close as in the few seconds the image is likely to be on screen slight artefacts will not be seen.

Text and fine detail give bigger files and show more problems for the same quality setting. Be careful about sharpening images that are to be JPEG compressed. Use the minimum that gives an improvement. It is always a temptation (I know, I fall for it many times) to add a little more sharpening than the image needs. This causes much bigger files and the increase in JPEG artefacts may make the image look worse than if it was much less sharp.

[Guest guru]

Only two cents...

I just tried few compression options, to verify what I had already noticed. I took a fine detailed architectural picture with a clean blue sky, sized at 1024 x 768 and saved as BMP (2.25 MB physical size, identical for any 1024 x 768 pixel images). Quickly optimized sharpness and noise with DCEnhancer.

In Photoshop the Jpeg quality (I looked at preview at 200%) began deteriorating in visible manner under quality 6; at this compression ratio, the resulting Jpeg was about 270 KB. A similar quality is gotten by "Save for Web" option (45/50), but this time the file size decreases to 240/250 K.

Starting from the same BMP, I made a Jpeg compression with Irfanview at quality 80. unluckily, Irfanview doesn't allow to verify in real time the picture quality, but at this compression value I got a 247 KB Jpeg.

Comparing at 100% (actual pixel size = 1024 x 768 full screen) I haven't seen any difference between the three Jpeg's; at 200%, the Jpeg made by Irfanview was the (slightly) best one, followed by "web saved" and "normal saved" PS, not distinguishable.

Ok, this is not a scientific test. I didn't reproduce optical targets, nor published 10x enlargements, and not even measured lines/mm or MTF values. But my purpose was only to start a discussion, and stimulate you to do similar tests.

Hope someone will tell us his opinion...

[DaveG]

Hi,

Thanks for the discussion, advice, comments all of which appear to bear out what I said. I have tried all of the various compression ratios within Photoshop and also the Save For The Web - they all give adequate results but only when the final product is a JPEG of around 250Kb - 350Kb. When the picture being compressed does not include large areas of, for instance, clear blue sky I could probably get away with a smaller file size but not the 80 - 150KB file size mentioned regularly. I have settled on using something called ProJPEG (BoxTop)..

ProJPEG

..which allows you to dial in the final file size required and this gives results equal to if not a little better than anything that Photoshop offers. It also allows smoothing of the final image but with a loss of fine detail. I leave that set to zero.

MikeL117's comments make a lot of sense and I will look out for that!! Perhaps the answer is selective sharpening?

Guido's findings again indicate that the optimum file size for a full screen image is in excess of this magical 150Kb which I have failed to achieve at a quality which satisfies my standards.

Ron - we are near neighbours - we must talk.

Thanks to all,

DG.

[Alan Lyons]

Hi all,

I just thought I would throw this into the discussion. The file size you deside to use is determined by the way the show is to be published. If you have to email or uploas to a site then the smallest possibli file is best. But if you are distributing on a CD or especially if you entend to project then is a small file nessary? The only thing that comes into play at this stage is the unknown prosessor capabilities of another machine.

In projection your 2:3 image is usually 1024 X 768 pixels but may be projected at 30ft X 20ft!, and if it is in competition they tend to sit the judge(s) front and centre some times less than 10ft from the screen. Even with 35mm film this can be too close for comfort.

My tack would be, use the best quality that the delivery system allows. As the old saying goes, "Don't ruin the ship for a hap'orth of tar"

Alan

[DaveG]

Hi Alan,

In this case the "delivery system" would be my monitor. If it doesn't look good there it won't look good when projected. When I get to projecting it that presents a new and different situation and possible problem to solve. Does that make sense?

Many thanks for your input,

DG.

[Alan Lyons]

Dave,

I would say if it looks good on the monitor it does not hold that it will look good for projection. As an example take a random image from a web page, these tend to be about 300 pixels wide. Put into your photo editor and zoom in. you will see the quality fall off as you go.

I don't know if you have film experience or have worked in digital only, but the maxim for film is, get the best possible negitive and when you enlarge the quality will hold for longer.

What compression does is remove pixels from the image, say, 1 in 5. This is not apperent at small sizes but as you enlarge, well you know the rest.

Oh! don't forget, it's the weekend, so enjoy,

Alan