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Rationale for 16-bit browsers lacking PNG support

Andrew T.

Experienced Member
Joined
Oct 4, 2013
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Location
Thunder Bay, Canada
Here's an issue that's been dwelling on my mind for nearly 20 years, back to the days when I still encountered Windows 3.1 on a daily basis:

Why do no 16-bit versions of Netscape or IE contain support for PNG images?

The last 16-bit Windows versions of the "big two" browsers were Netscape 4.08 and IE 5.01. Neither are capable of rendering PNGs. Yet perplexingly, the 32-bit incarnations of the exact same versions do contain PNG support! Windows 3.1 users were denied functionality that Windows 95 users took for granted when browsing the web.

For a while, I presumed that this happened because there was something intrinsically 32-bit about the PNG format itself...but the 16-bit version of Opera 3.62 renders PNGs without issue (aside from a lack of transparency), so that shoots a hole in that theory.

Any ideas?
 
Thats a good question. I always assumed it was due to speed and memory usage reasons, but it could have just been as simple as a 32-bit code library that they couldn't be arsed to port to, what they saw at the time, was a dead-end architecture.

There were some third party plugins for rendering PNGs under Windows 3.1.
 
There were a couple of Win16 web browsers with rudimentary PNG support. http://www.libpng.org/pub/png/pngapbr.html has a list from 1999.

The reference libraries which Netscape used were 32-bit. IE had such broken support for PNG early on that not having it in 16-bit was a benefit. Not seeing an image is better than crashing.
 
I seem to remember that when I started browsing with the NCSA Mosaic browser for Windows 3.1, it used the WIN32S extension. Does anyone recall this also? So sort of 16-bit, but with chunks of 32-bit code.
 
I can't remember what NCSA Mosaic used, but PATHWORKS Mosaic 1 and 2 (DEC licensed Mosaic) were both Win32s applications.
 
I remember back in the Internet Explorer days, Microsoft put in the about Internet Explorer window saying they used the NCSA Mosaic browser coding to produce the web browser.
 
I don't remember PNG being a common format back in the days when these browsers were relevant. It existed, but not many editing tools saved in it, and it just wasn't used very much. Losslessly storing 24-bit color wasn't relevant for 99% of Windows 3.1 users. The web ran on GIF and Jpeg, Windows tools used BMP & PCX, MacOS had its own formats and even Amiga IFF/LBM could still be found.

When did MSPaint start supporting PNGs? Wasn't that with WinXP?
 
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I don't remember PNG being a common format back in the days when these browsers were relevant. It existed, but not many editing tools saved in it, and it just wasn't used very much. Losslessly storing 24-bit color wasn't relevant for 99% of Windows 3.1 users.
I think this is the most likely explanation. I don't recall PNGs being particularly common until the early 2000s, well after 3.1 was no longer mainstream (and they didn't start to become ubiquitous until closer to 2008 or so, after even IE had mostly functional support for them.)
 
It's the history of GIF that's the backdrop of the reason for PNG (which was developed ca. 1995) as an open, unencumbered alternative. It wasn't the format or structure of the GIF image per se, it was the use by the CompuServe developers to incorporate LZW (Lempel-Ziv Welch) compression into the format--a patent for that was held by Unisys. LZW was initially proposed as a method for hardware compression (I've got the IEEE Computer rag where it was described). The CIS team didn't realize that it was a patented algorithm (neither did a lot of people) for software compression.

Unisys sued CIS and hammered out a licensing agreement with CIS where CIS as the sole licensee attempted to take on ensuring that all application of the compressed GIF algorithm was universally observed. This soured a lot of people and so the PNG format as an open, non-proprietary format was introduced as a replacement circa 1995. Others simply dropped the LZW compression and distributed uncompressed GIFs. Unisys offered a license for LZW compression on GIFs for a one-time payment of $5000, which resulted in very, very bad publicity for them. I remember the "Burn all GIFs" reaction. The Unisys patent expired in 2003.

PNG never really caught on during the 90s, which is why you don't see it on many 16-bit browsers. After 2003, of course, the subject was moot.
 
Thanks for the responses so far.

It could have just been as simple as a 32-bit code library that they couldn't be arsed to port to, what they saw at the time, was a dead-end architecture.
The reference libraries which Netscape used were 32-bit.
I had a feeling that at least for Netscape, the reasoning was going to be something like this. (Anyone want to dig through their 1998 source code release to confirm for sure? :p) PNG support surfaced in NS 4.04 in late 1997, and the decision to drop 16-bit versions from NS 4.5 forward might have already been made by then.

Yet a year earlier, Netscape pulled out the stops to get Java (which is intrinsically 32-bit) working on Windows 3.1.

I think this is the most likely explanation. I don't recall PNGs being particularly common until the early 2000s, well after 3.1 was no longer mainstream (and they didn't start to become ubiquitous until closer to 2008 or so, after even IE had mostly functional support for them.)

I was inclined to be an early advocate of PNGs, but the lack of 16-bit browser support dissuaded me from actually using the format for years. To me, the ability to make tightly-compressed high-colour images without dithering or degradation was the biggest point of appeal...ticking off Unisys was the cherry on top!
 
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