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Author Topic: OLD Digiview Format to be converted.  (Read 4253 times)

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Offline amigaksi

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Re: OLD Digiview Format to be converted.
« on: July 30, 2008, 07:23:06 PM »
>by Rowbeartoe on 2008/7/30 12:11:41

>JPG sucks so I will never convert anything to JPG. BMP, PNG, or TGA keeps pictures identical to the original.

I also avoid JPG.  However, you'll be amazed to see how many people are in illusion thinking JPG does not distort the original image especially after repeated editing.  And I have no idea why some people think digital cameras that use the lossy JPG are better than analog cameras in resolution.  They are higher in price but not in resolution.

It's okay to use lossy algorithms if you know what you are losing (like going from 8-bit/primary to 4-bits), but you probably need PHD in math to understand what you actually lost when you converted from GIF/PNG to JPG.
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Offline amigaksi

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Re: OLD Digiview Format to be converted.
« Reply #1 on: July 31, 2008, 09:05:07 PM »
>poo pooing on jpg format is inane. There is a time and a place for jpg, and obviously you don't do multiple edits on that format. It's also obvious you don't convert low color images to that format if you want it to look good.

The general consumer does not know the technical details of where to avoid JPGs.  I have seen some medical people using JPGs of medical imagery.

>Consumer cameras save to jpg because people can't see the difference in their pictures between raw because consumer cams don't have the quality for raw to make a difference anyway.

Yes, they do.  It's better to have a digital camera save to lossless format than lossy JPG.  There was a time and place when you couldn't because memory was expensive, but now they should avoid lossy algorithms.  Most consumers can't tell the difference between an 800*600 image interpolated to 1024*768 and an original 1024*768 but still the 1024*768 is better.

>Obviously you do your editing in a lossless format, and when you're done you publish in a lossy format unless your image is line art, screen shots or low color pix of crap you scraped off your amiga.

Some things don't require 24-bit RGB like cartoons or even hand-done paintings but that does not make them "crap".  

>That pic of the beach during sunset is going to look the same to people whether it's a tiff or a jpg, most of human vision is stuff being just plain made up in the viewers brain. This is why people use JPG, the result is about the same and it takes up a lot less bandwidth.

That same sunset in 24-bit lossless compressed format is better than JPG.  Would you archive a Mona Lisa in JPG or lossless compression?  And you can also subsample the color space 4:1 in each axes and interpolate it with luminance and get an image which human vision can hardly distinguish from the original.  And if you can losslessly compress the luminance and chrominance after delta-modulation, you get more than 8:1 compression easily and you know exactly what you have lost rather than doing a discrete cosine transform and quantizing the coefficients and not knowing what you lost in the spatial domain.

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