Laura! No! Don't do it!

Click through for the rest.

Grow into these trousers... >>

I can't think of a title for this post

I blog about many and varied different topics; but quite often, when I have found something unusual/interesting/amusing that I want to share, I struggle to find a snappy title for the post. I lack the ease to find a simple phrase which ties in the ideas I want to express. Other people seem to have a fluidity with words which I can only emulate by protracted cogitation.

Then I thought; does anyone else have my 'strapline' problem? Do you have to ruminate hard or does a headline simply pop out whilst writing or thinking about it?

Anyway, here is a song by Dan and Dan, who I just discovered.

The Daily Mail Song*


and of course it evoked this memory in me:

Bob Dylan- Subterranean Homesick Blues

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*Note: The Daily Mail is an influential UK newspaper. Grow into these trousers... >>

Colour is complicated - part 2

Part 1 is here.

I'm going to try to carry on from where I left off last time. Eventually I will get to primary colours and try to get my head around the colour yellow; it's a long journey though.


White light is a mixture of all the colours, as Sir Isaac Newton demonstrated with a prism. Different wavelengths bend differently at the interface of air and glass (or rain droplets) and this disperses the colours into the familiar rainbow spectrum. Blue light bends the most, red the least. The mnemonic “Richard Of York Goes Battling In Vain” is an aid to the recall of the colours of the rainbow - Red, Orange, Yellow, Green, Blue, Indigo, Violet. From the outside in!

Light continues at wavelengths beyond our vision. At longer wavelength than red is infrared which we feel as heat, but cannot see. Shorter then violet is high energy ultraviolet, which ages the skin and can trigger cancers - 'Slip-Slop-Slap' as the Australians say!

I don’t have an image, but Newton went on with a lens and another, inverted, prism to re-combine the colours and produce white again. Proof that white light contains all visible colours.

It is the colour dispersing nature of prisms which leads to chromatic aberration in lenses, and the complex optics needed to avoid it. But prisms, or their grown-up cousins diffraction gratings, can be used to split colours very finely to give almost single wavelengths, so-called monochromatic light, and this gives the fascinating science of spectroscopy.

So different colours are different wavelengths of light, and mixing all wavelengths gives white light, but what the hell is white paint?

It turns out that the energy carried by the visible wavelengths of light falls inside the region of the energies of electrons in atoms, and the vibrational energies of the chemical bonds between atoms. So if a bond is hit by just the right wavelength of light, it will absorb it and vibrate at that energy. A different wavelength will just pass through (transmit) or bounce off (reflect). The absorbed energy buzzes around for a bit till it's lost as heat and then the bond can absorb at that wavelength again.

A white surface reflects all visible wavelengths. It may well absorb wavelengths in the infrared or ultraviolet but we simply do not see that.


In white light a white painted wall is white. However, if you shine red light on it, it reflects red and looks red to the eye. Reflected blue light appears blue, green is green and yellow is yellow.

Now a white painted wall is not a mirror. Microscopic irregularities on the surface scatter the reflected light in all directions, when you have a perfectly smooth surface it reflects without scattering and the eye can reform an image. Glass can do this and, with a silvering behind it, we have the mirrors we all know. Frosted mirrors, or a frosted bathroom window, looks white because everything scatters.

So far we have been reflecting everything. What happens if the surface des not equally reflect all the wavelengths of light? What happens if some wavelengths are just absorbed, and vanish? Welcome to the real world of colour!

If I have a paint which absorbs red and blue light, and reflects green, it will look green to our eye.


Similarly, reflect blue and absorb everything else and you get blue. Reflect only red and you get red. Black absorbs every wavelength and reflects nothing.

If you want to make pink paint you mix white and a bit of red. The white part reflects everything, the bit of red still reflects red but absorbs a bit of everything else. The mix makes the shade.

I know this is all a big simplification because we haven't thought about the human eye yet, and the way we detect colour. I'll have a stab at that next time. Grow into these trousers... >>

A thought for a Sunday

"I still find each day too short for all the thoughts I want to think, all the walks I want to take, all the books I want to read, and all the friends I want to see".


John Burroughs (1837 – 1921) Grow into these trousers... >>

Disturbingly creepy

But hauntingly beautiful...

"Resonant Chamber" - Animusic.com [4:27]

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Via Grrlscientist. Grow into these trousers... >>

RIP mate

I just learned that one of my best friends has died. He fell ill at the beginning of the year and was diagnosed with an aggressive lymphoma. He lost the battle today.

We met in a pub, where else, and found we had a similar sense of humour, tastes in music, a love of good conversation and a fondness for quality beer.

He ran an electronics repair shop and, in the 15 years I knew him, he taught me more about how CRT televisions and monitors work than anyone really needs to know.

He was one of the rocks I beat my heart out upon when my marriage broke up.

I'll have a couple of pints of Ossett Brewery's Excelsior in your honour.
Cheers Jerry. Grow into these trousers... >>

Evening music - The Rezillos

I've been too much serious in my posts recently. I have to blow off some steam.

Rezillos - i love my baby cos she does good sculptures
Grow into these trousers... >>

Colour is complicated - Part 1

[Takes a deep breath]

When I posted Colours, files and compression on Saturday I knew I was going into a subject which few people would understand or even think about. FFS I don't really understand it :)

In no way was I dissing JPEG. For holiday snapshots and internet posts it's perfect, but it is the mp3 of photography and I'm advocating care and awareness when editing. How would it be if you opened a text document and 1 in 100 random words were subtly misspelt? Or 1 in 1000? Where is the tolerance threshold?

In that last post I tried to explain a bit about how colours are stored on your computer, but I only intimated that the same information is used to activate the glowing pixels on your monitor (or a TV). Each pixel on the screen has a red, a green and a blue light-emitting segment; the mixture makes the colour of the pixel. Get a magnifying glass and look at your monitor screen.

Red, green and blue (RGB) I called 'primary colours' and Jill asked

"I was an art major so I know the three primary colors are red, yellow and blue, but your example replaced yellow with green. Please explain. Thanks!"

You're correct Jill, everyone who has done any kind of art class knows the primary colours are red, yellow and blue.

So WTF Holroyd? Well, anyone who has done any kind of physics class knows the primary colours are red, green and blue.

Note, and I'm not being smug, in Saturday's post I was careful to say "...this is coloured light, NOT paint" and therein is a world of difference.

The truth is Jill and myself are both right, but to get the full picture we have to think about additive primary colours and subtractive primary colours.

To do that we need to know a bit about light and a bit about how paint interacts with light, but most importantly we have to consider how our eyes and brain decide which colour is which. It may take some time to get to a discussion of the colour 'yellow'.

So to start "What is light?" Well, if you want waves vs photons then it's neither, but that’s another post. I'll choose waves as a good model because they are familiar but, unlike water waves, the crests of all light waves are at the same height. They differ only by the distance between the crests of the waves - the wavelength. Red light has the longest wavelength, then green and then blue with the shortest.
This is a simplistic drawing but you may see there are 4 peaks of blue, 3 of green and 2 of red as wavelength increases. Where is yellow? At about 2½ on this scale (Arggg! I won't try to plot yellow it because the whole diagram is silly). The message is colour = wavelength. A consequence of physics is that short wavelength blue light carries more energy than long wavelength red light. This is the distinction, colour = wavelength = energy, which gives the beauty of a rainbow or indeed, the colour of anything.

I'm tired and can't concentrate no more.

To be continued... Grow into these trousers... >>

A thought for a Sunday

"Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't".


Pete Seeger (b. 1919) Grow into these trousers... >>

Colours, files and compression

I was commenting the other day at Elemental, my dear about Just Jill's photographs and I wondered what file formats Jill used when editing her fine images.

I humbly realised that many people won't know about file formats, compression, or even colour so I thought I'd do a serious post for a change.

I am no photography expert by any means, but I've done enough image processing to know it's a potential minefield.

I worked for a time using extremely low level fluorescence microscopy with a camera cooled by liquid nitrogen to minimise thermal effects. I was shut in the dark, in a tiny black painted room with a double door 'airlock' to keep out all stray light, and I sat there for hours listening to the radio, taking maybe 15 min exposures when all I could see was a faint, red glow from the laser illuminating the sample. Later I'd try to pick out the faintest of faint detail in the images. It became a skill, but limited to that type of image. However I had to know what the information in the image meant, in computer terms, so I could manipulate it without losing anything or, even worse, introducing an artefact that was not there in the original data.

This brings me to colour depth and file formats. Not all file formats are the same, some are 'lossy' meaning they really do lose data when you save your image. When you open the file again it 'recreates' the original as best as it can, but it is not the same. JPEG is the prime example and a good analogy is with mp3 audio files. Mp3 tricks the ear by removing things the brain won't miss using a psychoacoustic model. JPEG tricks the eye with strange, Fourier transform-like mathematics, which is very efficient in saving space but rarely unfolds back to an exact copy. I'll show examples of this later and, because you have a computer, I bet you've seen these artefacts before.

For these examples I'm using an old, free version of Paint Shop Pro, because it's basic, simple, it works and I like it, and I'm using 24 bit colour. Now, what does that mean? Think of the three primary colours red, green and blue (RGB), all bright and saturated. Now mix them together remembering this is coloured light, NOT paint. You can make yellow, cyan, magenta and white. You can make black too, just turn the lights off.

24 bit colour assigns 8 bits to each primary colour, and in binary 2⁸ = 256. This gives 256 brightness levels to each colour with zero being off/none/black and 255 being saturated. Think R,G,B (a triplet of numbers separated by commas) then bright red = 255,0,0. Similarly green = 0,255,0 and blue = 0,0,255. Black is 0,0,0.

Red + green gives yellow = 255,255,0 and I can make any darker yellow by mixing lower, but equal amounts, of red and green, this is 200, 200,0.

How to get a paler yellow? Well, 255,255,255 = white so you have to add some blue. The background colour on this page is 255,255,238.

When red=green=blue you get a grey. This = 200,200,200. Note there can only be 256 greys in a greyscale image including black and white.

How many colours in total?
256 x 256 x 256 = 2⁸ x 2⁸ x 2⁸ = 2²⁴ = 16,777,216

And that is what we get unless you spend a lot of money on a dedicated Macintosh or Silicon Graphics workstation, then you can get to 30 bit colour which gives 2¹⁰ (1024) shades to each primary colour for a total of more than a billion colours. I doubt the human eye can discriminate so finely but scientific data is different. If you see it advertised as 32 bit colour it's bullshit, it will be 24 or 30 bit with layers and transparency.

So how do we save over 16 million colours in a file? Think of a tiny 100 by 100 pixel image; that's 10,000 pixels, every one with 8 bits of data each for red, green and blue. 8 bits = 1 byte so it takes 3 bytes per pixel to store the colour data, or 30 kilobytes for the file. Then there will be some identification tag so the system knows WTF the file is, and basic stuff like height and width. I just saved a 100x100 px pure white image in different formats and Windows reports the file sizes to be:

Windows bitmap (*.bmp) = 29.3 KB
About what I predicted if you strictly save all 24 bits of data.

JPEG (*.jpg) = 823 bytes
Quite a saving! Plus it displays perfectly, not a blemish. This is not always the case with JPEGs though as I will show.

PNG (*.png) = 289 bytes
The compression of PNG can be amazing. In this case it will just record the fact that "everything's white" and that's all you need. PNG will however faithfully recreate the correct 24 bit RGB colour data for every pixel. The payback is that the file sizes soon exceed JPEG for complicated images.

TIFF (*.tif=1.31 KB) and TARGA (*.tga=418 bytes) both have good compression and again will keep full 24 bit colour.

GIF (*.gif) only has 256 colours in a defined pallet and you can't mix them. It's not a fair comparison (so I won't), but GIF is good for greyscale because there are only 256 shades of grey you can display (8 bits). Having said that, be careful with converting to GIF from 24 bits as there are many ways to interpret the darkness or shade of a colour. GIF is good for drawings, cartoons, charts etc which have a strictly limited number of colours. GIF also supports simple, frame to frame, animations and was the internet favourite before the full colour Flash.

To continue I'll concentrate on PNG and JEPG because both are 24 bit and fully internet supported. I'll show the differences by doing three edits of an image and I have chosen the colours deliberately because I know it will f**k up JPEG. The same will be happening in any image you repeatedly edit, you just may not be able to visually discriminate it.

I started a new image and made a smooth colour gradient from red (255,0,0) to blue (0,0,255) and then drew a green (0,255,0) line. Then I saved it as a PNG (left). The same colour data was still on the screen so I saved a copy as JPEG (right), just using the default settings. Then I closed my original image and opened the two new ones. Here they are!








Look carefully at the JPEG image on the right. There are clearly colour distortions. If you don't believe me, save them both and blow them up yourself (or, if you use Firefox, then right click on an image, hold down the Ctrl key and left click 'View Image', on the new tab hold down Ctrl again and spin the mousewheel to zoom).

My three edits will only add three words of white text to each image. Nothing fancy, and with no antialias so the edges of the text should be blocky and sharp. The PNG I will save as PNG, the JPEG I'll save as JPEG. Each time I add text I will save the file, close it and reopen it for the next edit.

First edit







If you can't see the distortions of the JPEG by now get a better monitor or spectacles.

Second edit







Third edit







And all I did was open-edit-save-close, open-edit-save-close... Look at the white text in the final JPEG, its not all white! But it's roughly acceptable to the eye for a blog post. This happens subtly to all colour boundaries in JPEG so it's not good for photography; you need to preserve exactly what you have on the screen when you save and JPEG will not do that. If this were an mp3 you would be moaning about scratchy, poppy distorted sound, but our eyes are more forgiving. Beware!

I know most digital cameras spit out JPEGs, and this is to conserve memory, but you may have an option for some kind of 'raw' format which, though it will absorb all the camera's memory in just a few shots, will give a bitmap (*.bmp) in some way. Save and edit that and then, finally, make your masterpiece into a cheap and nasty JPEG for the punters.

If you have to start with a JPEG then save a copy as PNG and work with that. Do the edits, and the last thing is to save a final copy as a JPEG again. Look at the file sizes though, the tradeoff between quality and file size may sometimes make PNG the better file to post.

I hope some of this makes sense. I've been up all night, the birds are singing outside, it's been raining and one of my cats just came in soaking wet. She jumped on my lap and gave a shake of drips everywhere. Thank you Titch but the mackerel for breakfast is mine. Goodnight/day to all :) Grow into these trousers... >>

Late night music - Martin Taylor

An accomplished jazz guitarist, solo.

Martin Taylor - Georgia on my mind [4:53]


By 'accomplished' I mean this kind of thing:

Martin Taylor with Stephane Grappelli [2:25]
Grow into these trousers... >>

Careful With That Axe Gun Eugene*

I was reading a post on thrust in rocket engines at Starts with A Bang and he used this video to demonstrate recoil, or Newton's 3rd law. It had just the right amount of chuckle to kick-start my morning.

Recoil Music Video [3:29]


* Why I thought of this I don't know.
Pink Floyd - Careful With That Axe Eugene [7:49]
Grow into these trousers... >>

Late night music - Sex Pistols

I've been thinking too serious tonight. So to even up...

Sex Pistols - Anarchy in the UK Studio Version
Grow into these trousers... >>

Ah, memories

After posting about tumblers and jugglers the other day I found this video and went "Ooh ooh - I know there".

Unicycling Down 50 Stairs - University of Leeds [0:31]


See the wiggly bench at the start? I often used to sit around there for a coffee and a smoke. The Faculty of Biology, where I worked for years, is off picture to the right. The skateboard park is just up the road at Hyde Park (that's Hyde Park in Leeds, not London) and other shots are round about the Student Union.

The yellow staircase I know well, Maths is to the left, Physics and the Computing Service to the right. The main library is at the top and then the university's main entrance. I have walked up and down there many times. Often to nip over the road and get a sandwich for lunch, but once to meet a certain NobblySan!

Here's more of the unicycle guy, similar places but some shots near the infirmary.

UNICYCLING IN LEEDS [1:25]
Grow into these trousers... >>

A thought for a Sunday

"I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world".

Albert Einstein (1879 – 1955) Grow into these trousers... >>

Late night music

After my previous musical offering I feel the need to cleanse my spirit.

In These Shoes Kirsty MacColl
Grow into these trousers... >>

So painfully bad, it's brilliant

I... can't... laugh... any... more...

Make it stop. Please...

Trololo (All song)


This being the Internet, there are many parodies out there but I thought this was the best:

Russian Singer Eduard Khil Remix
Grow into these trousers... >>

Elemental Challenge

"March comes in like a lion and goes out like a lamb"

Just Jill challenges her readers to capture that well known phrase in photography, words or drawings. I choose words because, for some reason, it reminds me of buying my first house.

I moved out of my parents' when I was 26, that was in autumn 1981. A bit old some may say but, with a proper job 9 to 5 and playing in a band 5 or 6 nights a week, I was hardly ever there anyway. When the band split up, tensions at home rose and I realised the need for more independence than bed, floor or caravan so I went shopping for a house... Then I looked for something within my means to pay the mortgage. There were a few cheap terrace houses in the nearby towns but then a local property came on the market and it was like the Ideal Home Exhibition to me. A quirky little run down thro-terrace. One room, a kitchen extension stuck on the back but open to the room, 2 bedrooms, bathroom, an attic and a cellar! Plus it was just doors away from my childhood. See top arrow...


The bottom arrow is where I lived till I was about 9 or so. That was a rambling, detached house with lots of rooms and dusty attics and spooky cellars. Oddly, I can't remember who had 'my' house when I was a kid, but my neighbours on either side had been there since the ark. I came home.

This curious 'V' shaped block of houses points almost due North and, by the angles, none of the rooms were square as I found out when I tried to fit carpets or ceiling tiles :) The house faces NNE and that seemed to become important!

It was a cold and drafty first winter in my new house, but March brought a glimmer of spring. Then it rained and the wind howled on and off for days, battering the house till I thought the roof would blow away. That's the humble me, underestimating the skills of the builder... but the March lion was here.

There must have been some tiny gap in the lead flashing over my small bay window and one day the wind and rain conspired to find the exact angle of attack. I came home from work in the driving rain to find half the room awash. Pot plants* on the windowsill were drenched, carpet soaked. I ran for buckets and pans to stem the drips, and shifted maybe 5 gallons of water from the windowsill over the next few hours. The deluge subsided as the wind shifted, and that was it. It didn't happen again. Over the next days I remained ready with bailing vessels but, not a drip. So, as a hard up new home owner, I diligently ignored this as a freak occurrence.

Did March go out like a lamb? Yes it did, no more floods anyway, and the next year brought me a new freedom. Because money was tight, and I didn't have the earnings and nights out from being in a band, I began to read again - like I used to when I was 10 years younger and before I discovered sex'n'drugs'n'rock'n'roll - but with a renewed vigour. A quiet studiousness descended.

I already had a computer, a UK101 with 4K RAM (YES! FOUR KAY! I later upgraded to 8 and added a tape modulator so I could actually save things. It plugged into the telly), I'd assembled it with a soldering iron as a kit project whilst still at Mum and Dad's, but now I learned how to program. First in BASIC, then in 6502 machine code. I soaked it up like a sponge.

The next winter was even colder, but a mile of draught excluder tape and heavy curtains across the kitchen hatch kept out the worst. Two cats, thick rugs and subdued lighting made it cosy. Huge campaigns of Dungeons and Dragons were played out on that floor between myself and some good friends. We pushed back the furniture and, on a 4 foot square sheet of glass with graph paper underneath, felt tip pens, painted models and many different shaped dice, we had countless hours of entertainment.

Winter turned... Snow and frost became rain and wind. March roared in on cue, and bugger me if it didn't rain in again! Through the same window, and just on one damn single day when the wind blew the rain at exactly at the right angle. Having forgotten the previous March, one afternoon I was again frantic for pots and pans. But, like the year before, it was a short lived growl. I learned the lesson though. In the third year I had buckets ready (two days of drips, if memory serves), by the fourth I had moved across the village to where I live now. I never repaired the leaky bit, it counted the years for me and it was too much fun!

After all 'The Lamb Lies Down on Broadway' maybe, but not me.


The Lamb Live Down On Broadway - Genesis - Part 1
Uploaded by newcanadian. - Watch more music videos, in HD!

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* not that kind on a windowsill Grow into these trousers... >>

I bet the cops find this guy hard to catch

I've always admired tumblers and jugglers but this guy is great.

AZO Showreel 2009


The dice trick is excellent. I've never seen it before, but my physics head realised that momentum (inertia) was involved. It's explained in this tutorial - if you click the link be careful with the volume because it's all over the place. Grow into these trousers... >>

I wish I'd thought of this

It would have made a jolly jape when I retired last year. Click onwards to reveal the punchline.

From the bizarre but wonderful Toothpaste For Dinner. Grow into these trousers... >>

Equality means being equal

A couple of days ago was International Women’s Day which was widely celebrated hereabouts.

I had never heard of this before, but it seems a cause I can fully support, so in the true gentlemanly tradition of making amends (next time, tell me beforehand) and in belated recognition of the day (hope it went well ladies) here is the courageous Wafa Sultan speaking on the dangers of Sharia law.

Wafa Sultan on Sharia


Wafa says she has a petition, but the clip is a couple of years old and I can't find it. I have signed similar things before though. Grow into these trousers... >>

Time travel made simple

Every second of every day, we are in the wrong place when things of the greatest importance are happening elsewhere. But what if we could travel in 'parallel time' and be doing something else whilst those same events unfold!

Ladies and Gentlemen, I present:

The Con-Time Machine [5:00]
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Via GrrlScientist. Grow into these trousers... >>

I'm on a horse!

This made me chuckle. Great advertising and very slick camerawork, it's done in one shot with minimal CGI. There's a making of video if you can stand the rambling interviewer.

Old Spice - The Man Your Man Could Smell Like
Grow into these trousers... >>

The nerd in me loves this cartoon

Click onwards for the rest. Grow into these trousers... >>

A thought for a Sunday

"All music is folk music. I ain't never heard a horse sing a song".

Louis Armstrong (1901 – 1971) Grow into these trousers... >>

A bit of music

...before I pull up to the fire and watch a movie or something. Quiet and melodic just for a change, well sort of.

Jerry Garcia & David Grisman - Friend Of The Devil- Warfield Theatre - 12/7/91
Grow into these trousers... >>

Late night music

After yesterday's post I felt I just had to remind myself what a real rock-music video should be like :)

Gary Moore & Phil Lynott- Out in the Fields


The splat at the end is perfect. Grow into these trousers... >>

Simply stunning

A music video from the band OK Go. The song is not too bad - the engineering is amazing.

OK Go - This Too Shall Pass - RGM version
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Via Pharyngula. Grow into these trousers... >>

Rama

I don't think I've posted this before, and I'm quite surprised because I love this guy's enthusiasm. V. S. Ramachandran speaks at TED about the connections within the brain and how they affect the mind.

Vilayanur Ramachandran: A journey to the center of your mind [25:31]


In 2003 Ramachandran gave the BBC Reith Lecture and he goes into much more detail. Fascinating! Grow into these trousers... >>

Late night music - Pink Floyd

I haven't posted any Floyd for a while.

Dave Gilmour Shine on you crazy diamond Live 2007
Grow into these trousers... >>

Even Einstein made mistakes

In fact he made lots of them. But there was one which even Mr Albert himself called "his greatest blunder". In 1917, looking at his newly forged theory of General Relativity, he realised the equations predicted that the universe should be either expanding or contracting. Einstein's world view made him unhappy about this, so he introduced a cosmological constant to counteract such movement. After all, everybody 'knew' that the universe was static. He defended this position for years, even though there was no physical or gravitational reason for such a mathematical constant to exist.

In 1929 astronomer Edwin Hubble observed that galaxies appear to be moving away from us, and the further away, the faster they receded. The universe was expanding and Einstein could have predicted it years before. He considered this to be his big mistake and the cosmological constant was dumped.

Interestingly, in more recent years, observations show the universe is not just expanding, but accelerating. This implies a force pushing empty space apart. Mathematically, it is strangely akin to Einstein's cosmological constant. Perhaps the old guy was onto something after all...

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Dynamic Einstein generator from hetemeel.com. Grow into these trousers... >>