Reducing the file size of a PNG...[Resolved]

[Conflow]

Hi All,

This may be of interest to a few Members who are exploring PNG-Image Technology because it has some excellent

merits and is used extensively in Commercial & Industrial applications for all all types of Imagery exchange.

Here are some general facts:-

1)

If downloading Jpegs from Cameras those images should really be saved as PNG's for the reason that it is a

"Losslesss-Format" and supports 48.Bit Colour whereas the JPeg is limited to 24.Bit Colour. If using RAW from

the Camera there is no loss unlike JPegs where there is immediate loss.

2)

It is also use extensively in 'Post-Editing' of Images because of its 'Lossless' characteristics.

3)

When working in PNG's particularily when re-sizing Images - the max-compression factor is approx 3:1 (Lossless).

4)

If used with Fixed-Size Images when both are identical in Size (centimeters) the average compression from

PNG to JPeg is just on 6.5:1 ratio and rarely drops below 5:1 and then only with small Images ie: 300x200 pix.

4)

Another merit is when using Masks & Transparencies ~ the opacity factor is accurately adjustable from 0%~100%.

5)

Another feature when working in Numerals-Text-Objects and Line-Drawings ~ these are always sharp, no degradation.

6)

When working with "extra-large" Camera or Saved Images ~ its better to immediately convert these into PNG then

reduce the size to something managable ~work away on the smaller PNG Images~ then finally resize to JPeg as needed.

With new modern Computers, PNG Image-Size is becomming a thing of the past as are the 'grudges' and misconceptions

about this Technology. For those willing to experiment keep in mind the above facts and do read up on it with Answwers.Com

and Wikipedia. You will certainly see the difference when making Video-Images in the smaller size formats.

Brian (Conflow)

[trailertrash]

Slightly off topic of reducing the size of png images, but just to present a different option I think you should consider 32 bit alpha channel bmp format instead of png. PTE will compress bmp images making the slideshows only slightly larger in .exe size with no loss in image quality.

Tom

Tom will the Bitmap format preserve the transparancy of the outer edge?

Andrew