"PNG files are typically lossless and are always much bigger"

John, that's simply not true. Almost all of the images I use on my web sites are .png format because I find them to produce better visual results in a smaller file. I too use Irfanview for much of my image capture work. But when I save files I use the Irfanview Save For Web plugin.

Robert, I use IrfanVIew all the time and have never seen a 8X increase.
Here are the results of one very quick jpg to png test.
47K > 95K
2148K > 2220K
5029K > 3728K
41K > 80K
1584K > 5232K

Mike

Mike, did you use the Save For Web plugin in your tests?

Gary, all I did was use the built in batch converter and left everything at default.

Mike

Note that I said "typically lossless", there is usually no loss of image quality in a PNG file. PNG files do have a form of ZIP-type compression which can make the files smaller, particularly if they are graphics with large expanses of the same color. Even though PNG is designed as a lossless format, PNG encoders can reduce the number of colors used in the color palette to improve PNG compression, this is the method that the "Save for Web" option in IrfanView uses. Generally speaking, PNG files will be larger than .JPG files on real-world photographs.

In support of John:

PNG Format

Guys, I'm not disputing the attributes of PNG files. All I said was that PNG files are NOT always bigger as was originally stated.

Guys, I'm not disputing the attributes of PNG files. All I said was that PNG files are NOT always bigger as was originally stated. Absolutely true. As a corollary to that, most photo editing programs let you set JPEG compression to zero, so that too can become lossless.

So, can someone remind me why Vegas Pro prefers png's to jpegs, or does it really matter since the loss is almost not noticeable?
Using the defaults in Irfanview, the conversion to png still increases file size, so I might as well stay with the smaller jpeg.

thanks,
robert

Vegas accepts both JPG and PNG without fear or favour. If you lightly compress JPG, in practice no-one will notice the difference from a lossless PNG.

Vegas will be happier though, if the resolution of each image is not too much greater than the resolution of your video. If you plan to zoom in or pan, then the resolution should be appropriately higher.

"So, can someone remind me why Vegas Pro prefers png's to jpegs"

I thought it wasn't so much that Vegas prefers PNGs over JPGs, it's that PNGs support an alpha channel for transparencies.

There has been a rumor going around the forum for years (and I've probably said it myself) that Vegas handles PNG files natively but that has never been confirmed one way or the other. Vegas seems to be happier with PNG files. Regardless, Vegas must decompress whatever file format gets used and PNG files could decompress a bit faster than JPG files. This would likely be more noticeable when using image sequences. Other than that, there really isn't much to be gained by converting JPG files to PNG files as the visual damage has already been done by the JPG encoding.