street photo – Don't hold your breath

How much space does a person need?

Tolstoy’s answer was six feet. Let me change the question to how much land is available in Mumbai to each person. The land area of the island city of Mumbai is close to 68 square kilometers. The number of people in this area was last counted in 2011, and was 12.5 million. It may have decreased a little since then, but this number will serve. Take away a quarter of the city’s area for roads. That gives us about 35 square feet of space per person. That’s a rather small room. Take away another half of the land area for offices, and you decrease the space to 12 square feet. We begin to approach Tolstoy’s limit. What chance, social distancing?

In a place like this you learn to be alone in a crowd. You can spend a quarter of your life packed like sardines into a can called a suburban train, and live a complete life in the space between your earbuds. You can get off the train, walk home to your 35 square feet bed-sit, and count yourself a king of infinite space. But you may have bad dreams.

Which is why work-from-home is a wonderful idea. As long as you have a job which you can do over the internet, what is it really that brings you far from your family and friends, from that familiar place that you grew up in, to a crowded city like this? We discovered the freedom of the internet during the pandemic. Immediately after the end of the lockdowns, we began to travel during the week, working on a laptop that you could take anywhere that gave you a wifi connection. I saw sunrises over deserts and mountain lakes during this time. And I saw nomads even more adventurous than me: kayaking between meetings, climbing cliffs with phone and earbuds in backbacks.

What keeps us bound to these cities? The concerts and dinners, the art and the collegiality of the workplace can be sampled a couple of times a week. But I love to walk the streets of the city, alone, camera in hand, taking street photos. Would I be able to watch people in this way in any place other than a city?

Images of broken light

Like everyone with a smart phone or camera, I’ve been taking street photos for years. So there’s nothing particularly special about the ones you see here. You could just look at them and move on. Or you can treat them as a challenge. Can you tell where each one is from? Count the featured photo as numero uno. The rest are numbered in the caption for your convenience.

You could just try to guess the continent, say South America. Or the country, say Ghana. But there are probably enough clues in the photos to tell you more. If you play along, it will be nice to have the reasons for your guess. But you could just leave your answers if you don’t want to type so much.

Midweek mobile 9

Rooms with large windows get more light than those with small slits for a window. Similarly cameras with small aperture lenses collect less light than those with larger apertures. Another artifact that small openings give is not usually visible with the naked eye. You may think of light as traveling in straight lines, but it is actually a wave. Where that becomes visible is at the edges of the windows: it can bend slightly around windows, making edges look fuzzy. This is called diffraction. The same thing happens in photos: edges of things become slightly fuzzy. Diffraction limits the resolution of your photo, sometimes more than pixel size. In order to keep this as clear as possible, I’ll not describe apertures by f numbers, but by the actual diameter of the part of the lens which is collecting light.

Here I compare images taken with a phone camera and a bridge camera. The phone camera used a lens aperture of 12 mm. I used that to take the street photo of a lemonade vendor in Puri. That image came as a 9248 pixels wide jpeg (all photos are in 4:3 aspect ratio) which I’ve compressed to 1250 pixels wide in the featured photo. (I think the red is too bright, but sensors have a problem with red. That’s a topic for a different post.) The bridge camera used an aperture of 62.5 mm and gave me the photo of the dragonfly as a jpeg which was 4608 pixels wide. I reduced it to 640 pixels in the view above.

Here is a zoomed in view of the two photos. In both of them I’ve selected a part of the photo 1662 pixels wide, and reduced them to 640 pixels for use here. In the photo of the dragonfly I can begin to see noise in the background; it was a very gloomy day and the photo was taken during a monsoon shower. But the edges look pretty sharp. In particular the veins in the dragonfly’s wing are quite clear. In the photo of the cart I can see that different colours are beginning to bleed into each other at the edges.

Finally, here is a zoom into a section of the originals which is 834 pixels wide. The images are reduced to 640 pixels wide for use here. I can see aliasing artifacts in the handle of the bucket: the straight line of the edge looks like a jagged lightning bolt if you look closely. There is no such artifact in the other photo. The veins on the dragonfly’s wings are still pretty sharp, but the joints between planks in the body of the wooden cart look soft. This is the diffraction limit on the resolution beginning to show. Software corrects for it, but that creates other artifacts. The bottom line? You can’t use the 64 million pixels of the phone image to zoom in a far as you can with the 16 million pixels of the bridge camera.

Phone photography changes our expectation of the interaction of camera hardware and image so dramatically that it is worth rethinking what photography means. I intend to explore this a bit in this series.

Entering Mumbai

We came within sight of Mumbai on a beautiful golden afternoon. The rain clouds had been wafted away, revealing a beautiful soft blue sky with high cirrus clouds. We entered from Thane. This was once was the main harbour in this region, then a sister city to Mumbai, and now, effectively, a suburb. The distant mountains looked much as they would have to the Malabari and Arab traders who used to sail past this coast a millennium ago. What they would not have recognized were the artificial cliffs of high-rises. I’ve never seen Thane looking so beautiful. All pollution and haze had been washed away by the rain, the afternoon light was just about to turn golden. I turned my attention back to the traffic.

The city around me

When you’ve lived in the same city for a large part of your life, you start noticing what visitors often don’t see. In cricket-crazy India who even knows that there’s a football stadium and a dedicated football subculture (only very few of whom buy jerseys from the ManU shop next to the Hard Rock Cafe). And not many visitors may come by to see the vistas of the city painted on the walls outside the football stadium.

You notice the constant small crowd outside this ice-cream shop which has been selling ice-cream sandwich for three generations. The crowds formed ever since the shop lost its battle in court to stay in the place where people like me found it as they wandered out of one of the city’s major local train stations. Every day there are people as old as me coming with youngsters to memorialize one of the city’s old landmarks before it passes. We have been among them, bringing a niece here with her boyfriend.

You pass an unremarkable restaurant where you’ve had a couple of nice lunches maybe fifteen years ago, and stoop to take a photo of street cats hanging at the entrance. You tell them, “Yes, the fish is quite good here,” as you walk away. That’s what you’d come here for, and remember years later.

Or you are caught in a traffic jam next to a blank wall whose texture you’ve admired for years. You’ve always hoped to get a photo here, but nothing really happens against that wonderful wall. Now, as your car idles, you see a (possibly) interesting intersection of shadows, and you take a photo. Does it work? Somewhat. Perhaps. But you’ll still be on the lookout for a better photo to take against this empty wall by a busy road.

Maybe along a cluttered lane which you have not taken for forty years, you see a clean white-washed house. An entrance door stands open as well-dressed women pass in and out. A widow’s home! Curious. You take a photo, meaning to find out later what kind of endowment runs a charity like that. And who they help. There are always single mothers in need of help in this city.

One weekend you walk out of a convenient coffee shop, on your way to buying a growler of your favourite craft beer, when you see the Yacht Club looking nice in the sunlight. You juggle the cup and your phone to take a photo, and realize that you’ve caught Mitter Bedi’s studio in the corner of the photo. It’s not a great shot, but it is a homage to the first industrial photographer in India, one whose photos are a foundation of the visual language you know.

Or you pass one of those dead end alleys which has better potential for discarded garbage than the tourist trade. The sunlight makes you pause. You take a photo of a green metal gate, rusting quietly and unremarked. Remarkably, the gate fronts a tiny shop where someone repairs swivel chairs! I wouldn’t have paid it any attention if the shop was open.

Sometimes you notice how a little temple has grown over the years. In the middle of the business district what once was a little stone idol on the pavement has grown into an idol-encrusted south Indian-style temple. And some time in the last two years it has fenced off the corner of the sidewalk. It seems clear to me that the temple will grow in coming years. It is one of the constant changes in a living and litigious city.

Midweek mobile 2

A mobile camera is not a good camera in ways that photographers were used to thinking of. The lens is a toy. Four centwp-admin/wp-admin/wp-admin/uries worth of lens technology have been junked by two related developments. The most important? That about 95% of the world looks at photos on tiny screens when distributing likes. So you don’t need the sharpness that photographers of old wanted; sell megapixels instead. That translates to about 10 Mbytes for the featured photo when my camera saves it. I know from experience that even on my large screen I can easily compress it down to about 200 kbytes and most people would not be able to tell the difference. That means I can retain only 2% of what is recorded. And on my phone I could easily throw away another 90% of the information (retain just 0.2% of the original) and no one would be able to tell. Then why so many megapixels? Because when you start from a large format photo and compress it down to a small screen, everything looks sharp.

You might remember that when you last changed your phone the picture quality changed a lot. Is that all due to more pixels? In a big part, yes. I dropped my old phone too often and was forced to change it quicker than I normally do. In three years the number of pixels in photo from a less-than-mid-range phone had gone up from around 10 million to about 65 million. Now look at the featured photo. The architectural details look sharp, considering that the subject is more than 300 meters away, and it was taken from a car that was making a sharp turn at a reasonable speed. But look at the near-full size blow-up in the photo above. You can see that at this zoom, details are pretty blurred. I have gained the clarity of the featured photo purely by not looking at it at full scale.

But that’s not the only change when you get a new phone. You also get a different AI translating the sensor output into an image. And this technology, which is a guess at what is being seen, is improving rapidly. As a result, the distortions of a bad lens can still be interpreted better, and result in a reasonable image. Note that this phone can remove digital noise much better than a five years-old phone would have done. The darker areas of the photo are much more clean (the detailed view above has been cropped out in the featured photo). Also, notice that the new generation AI deals with non-white faces better than before, getting an impressive image for the man walking towards the camera. This improvement is a response to accusations of biased training of AI.

But another detail is technically very impressive. Notice the level of detail? I can see very clearly that he is not wearing a mask. This resolution is better than a fundamental limitation which is imposed on lenses due to the wave nature of light (something called Rayleigh’s resolution limit). This computational super-resolution is a statistical trick which improves the image by making a guess about the nature of the ambient light. The down side of all this AI? This much of computation has a carbon cost. When I use my phone only for communication, the batteries last three and a half days. Street photography can drain the charge in a few hours.

Midweek Mobile 1

Night time is the worst time for photography if you have a tiny lens. Anticipating crowds and rain on the eve of Independence Day, I went out to get some street photos, but only took my mobile phone. It does a lot of computation to deduce the shapes and colours of what is recorded. With all that computation that goes on between the light hitting the sensor and an image being saved in memory, newer and faster computational hardware has an advantage.

But did these results actually improve over the physical limitations of the small lens? In one sense they did. If and when the sensor and imaging involve chemistry, a small lens exposes less of the chemical on the film. The result was that photos look dim. We are used to saying under-exposed for such photos. The only way to make the image brighter would then be to expose the photo for longer. But that creates a problem we call motion blur. With computation sandwiched between the sensor and image, there is a third way: the brightness can be amplified. I saw that The Family gets a much brighter image with her phone than I do, because her camera software is set to amplify more. So the problem of under exposure is replaced by that of digital noise: when you amplify, both signal and noise are usually amplified together. Motion blur can still be seen though, in the featured photo, for instance.

In another sense, the limitations of a small camera remain. A lens which is half a centimeter across cannot see details smaller than a couple of millimeters at a distance of ten meters. But this fundamental limit of resolution is reached only when the sensor collects light forever. With limited exposure the resolution drops by a factor of ten or hundred. So the image always has to balance motion blur against lens resolution. You can see this at work (at least on a large screen) in the photo above. The scene was well lit, the camera was not in motion, but the image is not awfully sharp. The computational hardware has prioritized freezing the movement of people by sacrificing the light needed for better resolution.

I suppose these photos look sharp and bright enough on phones and tablets to gather likes on instagram and tiktok. Perhaps you are in a minority if you view them on larger screens. As it turned out, it didn’t rain, so I could have taken a better camera with me. But technique is what you develop when you have limitations. A mobile phone is less obtrusive when you want to take street photos, so it is a good idea to start using it more widely for serious photography.

Abandoned

Revenge photography is a thing. I should know. I took photos of this abandoned shoe on a dirt track in Corbett NP with a sense of vengeance. I blamed it for sitting in the middle of a track, and for being lost in a place where nobody walks. I was raging actually at the Smooth-coated otter (Lutrogale perspicillata) which had loped across the river bank and into hiding below an overhang without giving me a chance to photograph it. It is a threatened species, listed vulnerable by IUCN, and protected as a schedule 1 species in CITES. Each one of them otter know that it is its a duty to pose for a photo, not run for cover.

This post appears on schedule while I travel.

The gaze of the salesperson

When you look at a person from behind the viewfinder of your camera, you sometimes find an appraising gaze looking back at you. Such eyes belong to people who make a living by selling. I like long zooms for such photos, because you can see the initial appraisal still going on. The featured photo is of two auto drivers in Ujjain, a really ancient temple town. For about two thousand years the locals have made a living from the people who pass through. The best salesmen survive; others move away.

A colonial-era town in Myanmar may not have quite the same history of trade, but the calculation behind the cheerful call of the women trying to sell you a snack is clear. As you can see in this photos, their eyes appraise you, and the smile switches off the moment it is clear that you are not buying.

A walk through pre-Diwali street markets is always productive. In this photo, the young man, probably a recent arrival to Mumbai, is still trying to figure out whether a man with a camera is a likely target for a sales patter about fluffy toys. I wouldn’t have bought one, but I’m more excited by the neon pandas than the plush pikachu.

This photo of a man in Jodhpur’s market is one of my favourites. He’s pretty sure that I’m not part of this target demographic, but he’s still interested in figuring me out. I probably fall at some borderline between the various categories of tourists who visit the town.

An uncertain place

Watson’s Hotel, later called the Esplanade Building, was built between 1867 and 1869. It is the world’s oldest cast iron building. For years it looked like it would fall down at the slightest touch. Something is happening to it now, behind high barriers. I can see a scaffolding above the blue metal sheets. I hope it is repairs and renovation rather than demolition. It’s been a Grade II heritage structure for decades, but that did not apparently force anyone to keep repairing it.