IMAGE: A BUDDHIST MONK CHILD FROM ARUNACHAL

Saturday, July 29, 2006

Buddhist monk child at Tawang, Arunachal, India.



Exif: Canon EOS 350D, 100-400L at 100mm, 1/125sec, f/5.6, ISO 400, handheld

Also see: Some more images from Arunachal.

NIKON LAUNCHING NEW CAMERA

Monday, July 24, 2006

The details are not out yet, but Nikon's teaser ad on their site has already become pretty famous. The new camera is under wraps, which is going to be released in about two weeks. All that they have said is that it is going to be a 10.2MP camera, and the speculation is that it is an obvious replacement to D70/D70s. Well, the D70 is old enough that it can do with a replacement, but we will have to wait for a few more days to be sure.

MORE ON HISTORGRAMS

Thursday, July 20, 2006

These are a few points I initially wanted to cover in the histogram primer I posted yesterday, but they not only seemed to be a bit advanced, they did not seem to fit anywhere in the post. So here they are:

RGB HISTOGRAM

The histogram normally displayed to show the overall brightness of the image indicates the brightness of all three primary colors put together. Some cameras, and software like Photoshop can display histograms for individual color channels. It is important and useful to look at RGB histograms because they can indicate any clipping in individual colors, which may not show up in the brightness histogram. And if any color is clipped, it could result in some color shift, since the clipped color is not represented properly at areas where it is clipped.

HISTOGRAM OF RAW IMAGE

When we capture a raw image, the histogram shown on the camera is not of the raw image, but of a jpg image that was converted internally by the camera. The raw images being linear, histograms can't be drawn on it. While this is not a major problem, the histogram shown on camera may not be as perfect as it should be. The jpeg image generated by in-camera conversion may have some difference from the jpg generated by the conversion software you would use. So the histogram seen on camera could be different from that of a jpeg that you would generate with your favourite software. But that only means a slightly inaccurate histogram, which should not make a lot of difference in interpreting the brightness levels of your image.

EVERYTHING ABOUT HISTOGRAMS - A HISTOGRAMS PRIMER

Tuesday, July 18, 2006

Histograms are a vital tool that most digital photographers tend to use when taking pictures. This is a short and easy essay on understanding and using histograms in the daily life of the digital photographer.

HISTOGRAM, WHAT IS IT?

To say it shortly, a histogram indicates the brightness level of an image. Most of the advanced digital cameras, and probably all digital SLR cameras have the feature to display the histogram on the LCD. On my Canon EOS 350D, I need to press the info button twice to see it. It may be different in your camera. You can also see the histogram of an image after downloading it to the computer, using software like Photoshop.

Any digital image is represented by thousands of small dots called pixels. In a color image, each of these pixels will have two important characteristics - the color of the pixel and the brightness of the pixel. Let us focus on the brightness part. A pixel can have a brightness level from a pre-defined set of values. For simplicity, let us say we have brightness level zero to brightness level 255. Then, 255 represents the brightest possible pixel and zero represents the darkest possible pixel.

Now, the histogram is simple graph that represents this brightness level(zero to 255) on the horizontal axis and number of pixels for each brightness level on the vertical axis.

HOW TO INTERPRET IT?

It is easy. If your image is dark, then you have more pixels with low brightness value, which means that your graph will be tall on the left side. Similarly if your image is very bright, your graph will be tall on the right side. For an image that has lot of mid-tones, the graph will have its peak in the middle.

To demonstrate how histograms look, I took three different shots of the same object. The first was properly exposed. Second image was deliberately under-exposed and the third was deliberately over-exposed.



The above images are of a white wall lit by florescent light and its histogram. To the right of the image is part of a poster included deliberately to demonstrate the histograms. This is a properly exposed picture. Since the image is properly exposed, most of the pixels are concentrated to the middle of the histogram. The pixels related to black poster are concentrated to the left.



The above image shows the under-exposed image and it's histogram. See that the peaks of the histogram have shifted to the left.



The above image shows the over-exposed image and its histogram. As you can see, peaks are to the right as the image has many bright pixels.


Above images demonstrate that a histogram can be used to check the brightness level of the image. But it does not necessarily mean that all images with histogram skewed to the right are over-exposed, or skewed to the left are under-exposed. Some images may naturally have many bright elements in it. For example, snow being bright by itself, histogram of an image with lot of snow in the frame will have more bright pixels and yet does not mean that it is over-exposed. See the following image that has lot of snow. It is properly exposed, but its histogram shows many bright pixels, which is how it should be. Similar theory applies to dark images too.



BURNT IMAGES

If you have any pixels recorded at the right most level of the histogram, it could indicate a problem. It means that you have some pixels that are fully white or at level 255. Typically, it could mean that the image is very over-exposed and any details at this part of the image are completely lost, and all that remains is of white colors. This could happen often if you are photographing an area with snow, or bright sky. Some cameras indicate this with a blinking region on the images when you play back on the LCD to warn that the image is over-exposed. In my Canon camera, I need to press the info button twice to see this blinking display. The exact way to see it may vary in your camera.



In the above image the details of the grass on the earth outside the window are lost since it is completely over-exposed. Notice that there are some pixels on the extreme right of the histogram.

WHY IS IT NEEDED?

The histogram gives a reliable feedback on the exposure level of your image. The LCD display is not a reliable way to interpret this because what you see depends on the brightness of the LCD and not just the captured image. But the histogram will give away any areas that are too bright or too dark. It especially serves to warn about completely burnt pixels.

CANON L GLASS MANIA

Sunday, July 16, 2006

The premium range of lenses from Canon - called L series lenses have their own fan following. Revered for the quality and finish, some people love them like nothing else. The L glasses don't come easy, usually have a price tag that makes the buyers think many times before going for one. But the love for these glasses usually wins. All this has resulted in many jokes and quotes related to L glasses. A photography forum that I regularly follow has a large number of L fans and I often get to hear amusing quotes and interesting incidences. I even went ahead and created my own quote based on personal experience -

"Once L, always L!

I bought my first L, the 17-40L almost a year ago. The image quality of this lens was such that I no longer felt like shooting with my older lenses which were not L series, and ended up buying another L series lens - 100-400L. Together they cost me enough money that since then, I have not thought of buying any more photography equipment till date!

Here are some of the L series quotes and one-liners worth reading:

"I am not an Lcoholic. Lcoholics go to meetings!"

"You can take my 100-400L away when you pry it from my cold, dead fingers"

"L"et there be light!

And occasionally the letter L gets associated with Love! Very recently some one made the mistake of asking "what does L on certain Canon lenses mean?" and we were all rewarded with many funny answers!

JOHN HYDE'S PHOTOGRAPHS OF ALASKAN WILDERNESS

Friday, July 14, 2006

I bumped into John Hyde's website today and went completely crazy looking at the photographs he has got on his site. He lives in Alaska, and has put to good use his accessibility to one of the most beautiful wilderness in the world. Every image on the site seems perfect and a great treat to see. I wish he could write some tips about how to take such great images though!

RSP OWNERS GET ADOBE LIGHTROOM FOR FREE

Thursday, July 13, 2006

I got an email today from Pixmantec team, formally announcing Adobe's acquisition of Rawshooter technology from Pixmantec. The email also announced some good news for those who owned Rawshooter Premium RAW converter software - they get to download Adobe Lightroom 1.0 for free. Below are some excerpts from the mail.

"Offer a free download version of Lightroom 1.0 for customers who bought RawShooter | premium prior to July 12th 2006, 12 noon European Standard Time. Given that Lightroom 1.0 will serve a much broader range of functionality and will be priced at a higher price point than RawShooter | premium, we believe this represents a great value for our customers.

Adobe will investigate to what extent your image corrections made within RawShooter can be transferred to Lightroom.

We will deliver support for Canon EOS 30D In RawShooter | essentials this summer."

DIGITAL PHOTOGRAPHY WORLD MAILING LIST

Sunday, July 09, 2006

I had been toying around with the idea of creating a mailing list for 'Digital Photography World' for some time now. Finally I have it up and running. Emails to the list will be sporadic though I hope to send an email once in a month. Do subscribe to it by keying in your email address in the textbox on the right hand side.

BLOGGER'S BREAK!

Thursday, July 06, 2006

Just for 5-6 days and I shall be back again!

Meanwhile, an image of children from Arunachal Pradesh, India. One hyperactive kid and 3 normal! All sitting on single bicycle!!

GRITTINESS OF COMPACT FLASH CARDS

Monday, July 03, 2006

This is a small experience I had had with CF cards a few months ago.

I was then travelling in Tawang, Arunachal Pradesh in the north eastern parts of India. My CF card was nearly full and I went to an internet cafe to download and burn it to a CD. I had with me a full 2GB card, and a brand new card reader. I had forgotten to pack my card reader when I started for the trip, and was forced to buy a new one in the middle of the journey. The new card reader looked similar on top and bottom, and when I inserted my CF card into it today, I was holding it bottom up without my knowledge. So the card got inserted upside down, went into the slot partially and hung there loosely. Naturally, the computer refused to identify the card. I played around a bit for a few minutes without much luck. Finally, not knowing what is wrong, I applied some pressure and pushed the card into the slot so hard that I forced in the card to the slots upside down! I realized the mistake a little later, and assumed it would be the end of the card(and the images stored in it). Any electronic instrument would obviously splutter and die on such treatment, and I was worried it would be same with the card. I then put it back properly and tried my luck to see if the card still works. To my surprise, it did, and all the images were completely intact!

Later on, I have happened to come across stories of people dropping their card in the water, even worse, in the washing machine and coming back delighted to see that the card and the data are intact. Here is one such testimonial from Michael Fox, where he says:

"I found the card in the muddy water and immediately swung in to "save the card" mode. Despite being a piece of electronic equipment, I found a source of clean running water and rinsed the card of muddy sediment... ...Gingerly, I slotted the CF card in to a regular Lexar USB card reader, and waited for the card icon to pop up on my Apple Powerbook desktop. Within seconds, there it was. OK, stage one complete. I opened the folder and it listed 297 images, every single one I had taken, and all were 4Mb or 5Mb in file size, no zero-byte files."

And some one commented for the same story -
"I accidentally ran a 1GB Lexar Secure Flash drive through a wash and spin cycle in my washer and after allowing it an overnight airing atop a hot air vent in my house it worked perfectly"

IMAGE: CHILDREN OF ARUNACHAL

Saturday, July 01, 2006

These kids were pretty close to me and were moving quickly. I had my 100-400L mounted on the camera and had to shoot as soon as possible. I had to settle for a tight capture and not-so-great lighting. I also missed an opportunity to capture the kid in the back peeping out to take a look at us!



Exif: Canon EOS 350D, 100-400L at 150mm, 1/180sec, f/4.5, ISO 100