Friday, September 10, 2010

Snow on the Riviera

This is the French Riviera (close to Grasse), with a quite different look from what you might expect under normal circumstances. Snow is very rare here, and it will snow about once a year or every other year, and then it doesn't last. This is from last winter, when a snowstorm caught the entire region in one afternoon. Close to the sea it was gone in one night, but here it lasted almost 3 days before being completely gone. This is on the evening after the snowfall.

Obviously, for those living in areas where snow is common, this is just a very small amount of snow. But, considering where this picture was taken, this is an incredible amount of snow, that caused traffic chaos, sent people home from work in the middle of the day, and had people talking for weeks. Quite an event.

I like the sunset in the background, and the detail of the clothes "drying" outside the house. Those are the reasons for selecting this picture among the whole series. However the halo on the left tree bothers me; if I had been processing this picture now I wouldn't let this happen. You learn all the time.

This is a 3-exposure HDR, spaced by 1.5 stops, taken with my Pentax K20D and a 16-50mm f/2.8 lens, at 39mm, f/4.

Friday, August 27, 2010

Raw compression explained

This picture is from La Rochelle, in France. It's an old customs building, adjacent to the port's fortifications, in very good shape. La Rochelle used to be a very important French port during the Middle Age.

The picture is a 3-exposure HDR, taken a f/6.7, ISO 100, 19mm, tonemapped in Photomatix and adjusted in Photoshop (cleaned a corner with an annoying dark cloud, sharpened and increased detail in the bricks of the building).

It also shows the tragic fate of my 16-50mm f/2.8 Pentax lens: this one is among the most damaged pictures, just look at how soft it is on the right side. Fortunately I composed with the subject on the left side. :-)

Raw compression explained

I found this very interesting article today which explains what the mechanism and impact of Nikon's lossy RAW compression are. It has taken some time finding explanations that are scientific enough, so I thought I'd share it.

In very, very short: the lossy compression reduces the 12-bit depth to a 9.4-bit depth, but in a way that makes a lot of sense. Because the sensor captures light in a linear way, but we see it in a logarithmic way, the same absolute difference of tonal levels will have a lot of impact on detail in the shadows, while it will have less impact in the highlights. Or, to put it another way, the single brightest f-stop spans over half the sensor's range, while darker f-stops take up much less of that same range. Thus the lossy compression maps the sensor's recorded tonal levels with a function that does not alter them in the shadow parts but compresses them in the highlight areas, because you won't see the impact (it's almost a "waste" to have so many possible tonal values in the highlights, it's more than you can see). The potential negative impact lies in the heavy retouching work you might want to do to bring detail back: in such cases, posterization risk is increased. Go a head and read it, it will be clearer!

I have yet to make up my mind on whether to use this feature and save space, or turn it off and play it safe!

Saturday, August 21, 2010

Starting a photoblog ...

You have to start somewhere. I start with this.

The idea of creating a photoblog has been in my head for some time now. There are 2 reasons for that:
  • there are some really great blogs out there that are both a treat to simply browse and a source of inspiration; let's mention the one that might have been my biggest inspiration recently, StuckInCustoms by Trey Ratcliff, who is basically the world's HDR guru (although he happens to take non-HDR pictures from time to time, I believe!). Edit: One of his recent pictures does bear a resemblance to the one I'm posting here (well, it's a sunset, there's the sea... that's all I mean), but I promise, I made my choice before I saw his! As a matter of fact I first published this picture before he did, so that saves me from whoever might accuse me of stealing his inspiration. :-)
  • my own pictures are starting to be decent now; maybe, maybe, some guy or some girl somewhere in the world, who is not in my Facebook friend network, might enjoy looking at some of them. Who knows.

So... I'll give it a try, and see where it takes me. If you happen to stumble on this page, then do leave a comment!

I'll probably post pictures on a regular basis (but clearly not daily -- I don't have enough time, or good pictures, for that). Maybe I'll publish some articles about photo gear, software or processes, or post links to cool websites from other people.

Now for the first picture... I chose one from a recent vacation (back in June).

It's a picture from an island in the Red Sea, on which we spent about 30 minutes in the middle of a one-week diving cruise: solid ground, what a change!

There's nothing there but a tower of some sort, don't remember exactly what it was for, an eagle nest with its eagle on it, and a lot of trash left by previous tourists when barbecueing was not yet prohibited. And this cylinder, of course. I'll probably post a picture of the eagle taking off. I was lucky enough to be able to take a picture at the right time. Or maybe it wasn't luck, but the fact that I was in the middle of group of people walking decidedly towards the nest, and the eagle had nothing else to do than fly away. Damn tourists, right?

The picture itself is a 3-exposure HDR, 2 stops between each. f/4.5, ISO 100, hand-held. Processed in Photomatix and adjusted in Lightroom. I don't think I made any modification in Photoshop.