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Re: [hylafax-users] send me a color fax, please

On 2005.01.25 07:05 Sebastian Flothow wrote:
Am 22. Jan 2005 um 03:24 Uhr schrieb Lee Howard:
I've gotten a test number set up now with HylaFAX color fax support (JPEG) (receiving only).

Is the use of JPEG a limitation of the HylaFAX implementation of color faxing, or is it required by the protocol?

JPEG is required by the protocol for color facsimile.

Yes, JPEG is lossy. That's why there is also support in the protocol for *JBIG* color fax. However, per the spec, JPEG must be supported if you intend to also support JBIG.

JBIG support in HylaFAX is on the horizon. There are possible patent issues, though, that seem to prevent many manufacturers from using JBIG. So a lot of "color" fax machines support JPEG but not JBIG.

I'm asking because in my experience, low resolution images and lossy codecs don't mix very well, especially when stupid users are involved - I've had enough of text in JPEGs which are compressed to the point of being utterly unreadable. I can just imagine people sending vanilla b&w letters in color, simply because their fax machine has a shiny button labeled "color".

Yes, JPEG can be compressed into unreadability. However, with my experience thus far with color fax, it doesn't seem like a problem. The fax machines don't seem to be compressing the image into JPEG so much that the readability is lost. Yes, black-and-white text (well, anything with a defined edge) does have a "halo", but it's not extremely noticeable. I guess if someone were to bounce the color fax image back and forth a few times that the lossy nature of JPEG would eventually make the text unreadable altogether, but I don't think that most people sending color faxes are going to do that.


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