Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
So what file format was used in those days? TIFF, RAW....? No reason for asking - just interested.Flyfisher said:
- Thread starter charlie-ia
- Start date
Nemesis
Member
- Messages
- 9,402
- Location
- Planet Earth
Keep your back straight, and if it's too heavy for you, get someone to help you.
Ho ho.
I still can't see it myself! Many flues where this would be very difficult to do.
Ho ho.
I still can't see it myself! Many flues where this would be very difficult to do.
Flyfisher
Member
- Messages
- 10,200
- Location
- Norfolk, UK
We were digitising the photos using a video camera and a custom-built video framestore (that was my bit) that was designed to add colour photo to standard videotex - Prestel as it was called back then, same as Teletext today. Adding colour photo capability was called Photovideotex. We compressed the image data using a DPCM algorithm, which gave us 2:1 compression. The project was a contract for BT research labs in Martlesham and they had another team working on image compression. One of the BT team ended up as Chairman of the JPEG committee that developed the now standard jpeg format.Penners said:
Well you did ask!
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
I did indeed, and that's very interesting. I've never heard of DPCM image compression - only JPEG and LZW. Mind you, at only 2:1 I'm not surprised that it didn't stay the course.Flyfisher said:
I know the BT establishment at Martlesham - not what I'd call an architectural masterpiece, although I presume the "control tower" block was supposed to be an echo of times past. I taught Mrs P to drive there, when Martlesham was still just an old abandoned airfield (and yes - the relationship survived the experience!)
Flyfisher
Member
- Messages
- 10,200
- Location
- Norfolk, UK
DPCM is more of a technique than a name, a bit like DCT (discrete cosine transform) being the technique behind the named 'jpeg' standard. You're right about 2:1 not being much compression, but the image sizes were only 270x240 pixels (for an image the same size as a teletext screen.
We also separated the image into luminance (b&w) and colour components (just like colour television), which allowed us to send out a b&w photo first, followed by the colour. The idea being that the viewer could halt the download as soon as they realised they didn't want to see the entire photo and could therefore save time by not having to wait for the complete download. This sounds ridiculous today, with 2Mbit/sec broadband links, but those were the days of 9,600 bit/sec modems - i.e. over 200 times slower, so such things mattered. The colour separation also meant that we could use a lower resolution for the colour information (saving memory/bandwidth), just like colour television, so we had already reduced the data by 25% before the 2:1 encoding compression.
The system was used on cable TV systems in Westminster and Milton Keynes and was used by shopping channels and estate agents, where the addition of colour photos to teletext was a big leap forward. Singapore was also a big customer. But BT never managed to make a commercial success out of it and then that chap at CERN published his www ideas and the rest, as they say, is history. Interesting times though.
As for the 'control tower' at BT research labs, I was also told it was designed in homage to its airfield history (wasn't it the place that Bader had his crash?). But I was also told that the rotation of 45 degrees between the top and bottom parts was a mistake during the build and by the time they realised they decided to keep it that way. I suspect the BT guys were winding me up but I never did find out for sure.
I know what you mean about not being an architectural masterpiece, but it's certainly very distinctive and of it's time. I suspect there would be calls to list and preserve it if BT ever decided they wanted to pull it down.
(Phew; I managed to get the post back round to architecture after the 'period technology' ramble
)
We also separated the image into luminance (b&w) and colour components (just like colour television), which allowed us to send out a b&w photo first, followed by the colour. The idea being that the viewer could halt the download as soon as they realised they didn't want to see the entire photo and could therefore save time by not having to wait for the complete download. This sounds ridiculous today, with 2Mbit/sec broadband links, but those were the days of 9,600 bit/sec modems - i.e. over 200 times slower, so such things mattered. The colour separation also meant that we could use a lower resolution for the colour information (saving memory/bandwidth), just like colour television, so we had already reduced the data by 25% before the 2:1 encoding compression.
The system was used on cable TV systems in Westminster and Milton Keynes and was used by shopping channels and estate agents, where the addition of colour photos to teletext was a big leap forward. Singapore was also a big customer. But BT never managed to make a commercial success out of it and then that chap at CERN published his www ideas and the rest, as they say, is history. Interesting times though.
As for the 'control tower' at BT research labs, I was also told it was designed in homage to its airfield history (wasn't it the place that Bader had his crash?). But I was also told that the rotation of 45 degrees between the top and bottom parts was a mistake during the build and by the time they realised they decided to keep it that way. I suspect the BT guys were winding me up but I never did find out for sure.
I know what you mean about not being an architectural masterpiece, but it's certainly very distinctive and of it's time. I suspect there would be calls to list and preserve it if BT ever decided they wanted to pull it down.
(Phew; I managed to get the post back round to architecture after the 'period technology' ramble
)Nemesis
Member
- Messages
- 9,402
- Location
- Planet Earth
This might be of interest:
http://www.ahds.ac.uk/news/newsletters/autumn-2006/index.htm#2
I'd forgotten all about punch cards!
http://www.ahds.ac.uk/news/newsletters/autumn-2006/index.htm#2
I'd forgotten all about punch cards!
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
From punched cards or tape to multi-terabyte drives in one generation. It is really extraordinary.
Nemesis
Member
- Messages
- 9,402
- Location
- Planet Earth
I knew where I was with punch cards.
They didn't keep refusing me access to my e-mails for reasons I can't fathom!
They didn't keep refusing me access to my e-mails for reasons I can't fathom!
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
Luddite!
Nemesis
Member
- Messages
- 9,402
- Location
- Planet Earth
I haven't smashed it yet, but the temptation is great...
Flyfisher
Member
- Messages
- 10,200
- Location
- Norfolk, UK
I believe punched cards were originally used in Jaquard (sp?) looms to store the pattern 'programs', so they've been around for a bit more than a generation. But I entirely agree about the extraordinary progress in the computing sense.Penners said:
The first hard drive I came across was a Burroughs unit in the early 80s. It was the size of a 2-drawer filing cabinet, had a single disk about 12 inches in diameter and held a mighty 10 megabytes, i.e. enough for a couple of digital photos !
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
And still are.Flyfisher said: