Saturday, June 21, 2008

Photo Processing Example

photographyIn my last article I gave beginner's tips for taking Your Photos From Washed Out To Punchy. Now I'll step you through a real-life example, using a photo I shot just last week. I'll give you eight versions of the file, starting with how it came out of the camera and ending up with the finished product.

My example is the following view of Sywre Head and Bat's Head, on the coast of Dorset near Lulworth Cove. It's an amazing part of the world, a small stretch of what is now known as the Jurassic Coast, Britain's only natural World Heritage Site. There is a great description of the walk available.

This is the photo I started with, shot in RAW mode on the Pentax K100D Super with the Pentax DA16-45mm lens at 45mm. The exposure details: ISO 200, f/11, 1/400s. Click on each photo as we go to get a larger view. Of course these are still small compared to the original, but it should give you a reasonable idea of the changes.

It was near the middle of the day, slightly overcast. The light was hence not particularly favourable. And I had no polarising filter. So, although this isn't a bad photo by any means, it is a reasonable candidate for some tweaking.

In terms of composition I am happy with the 3:2 aspect and framing. I like how there are some bathers in the foreground. Tiny little dots though they are, they provide scale. The shoreline creates a natural s-shaped leading line into the centre of the image, while the cliff-side creates a more complicated but still pleasing vector for the eye.

I noticed though that the horizon is not perfectly straight. So the first thing I did was use PTLens to correct (very slightly in this case) for the lens and then the Measure Tool to straighten up the picture. Then I cropped to straighten the borders.

Notice what has happened? Due to straightening the horizon we've lost the foreground bathers. This is annoying and shows how important careful in-camera composition can be. Though to be fair I did get the photo nearly straight. Maybe I'll do something to rectify this problem later.

Next is a levels adjustment. I noticed that two of the channels have no information at the extreme highlights, so I pull in the white triangle slightly. The image shows this adjustment for the Green channel. Other than this I changed the center point of the RBG composite curve to darken up the image slightly.

You might think that's a minor change. Indeed all the adjustments I make here will be subtle enough taken one at a time. Fiddle too much and you risk creating an unnatural image that simply does not feel right.

Next I do a curves adjustment. I have several profiles saved so often all I need to do is load one up. The curve used here is a variation on a standard S-shape to increase contrast. What is different is that the white end is preserved so that highlights are not compressed.

After viewing this on the entire image I realised that it helps the cliff-face and cliff-tops but does no favours to the sand, water and sky. So I created a selection for this region and applied a mask to this curve.

I will not go into the details of masking here, but for some advanced techniques consider Contrast Masking and Tonal Masking.

You can see that the landscape definitely pops out more now. Loading up the same selection and inverting it I worked on the sea/sky/sand in the same way.

This curve is far more complicated since each of the three channels has a different adjustment. This illustration shows the blue channel, which has a more dramatic adjustment than the other channels. (Perhaps not surprising given the area of the image we are affecting.) Again, though this multiple curve may take a fair amount of twiddling to get right, it can be saved and applied in future similar situations.

Somewhere along the line the grass has become a bit too extreme for my tastes.

A Hue/Saturation Adjustment Layer with the same land mask I used before targets the grass. I choose "Greens" from the menu. You can use the eyedroppers to select the exact green if necessary. I toned down the saturation slightly.

This is the result after applying the three standard Layer Adjustments.

The photo above is after sharpening is applied. In fact, three different subtle sharpening layers are in operation here. It is quite common for different methods to be used to sharpen in different ways. One might alter local contrast while another might remove glare from the overall image. Sharpening is a vast and well beyond this tutorial. But you can learn a lot from Ron Bigelow's articles.

The final image. I just could not resist copying in the bathers that were lost to the original horizon adjustment. I do hope they will forgive me my indiscretion.

The great thing about working in layers is that going back to make this change required very little extra effort. Yes, there were two steps along the way that required flattening the image (for sharpening), but since I kept all the different stages in the one image file it was easy to replicate the steps.

Likewise if I had a similar image I could just throw it into the bottom-most layer and have a pretty good start on processing. Through a combination of re-using files, saving common adjustment settings and automation (by way of Actions or otherwise), it is possible to process a good number of images in a reasonable time.

Compare the final image with the original.

I hope it is apparent that the integrity of the shot has been maintained but that its impact and clarity is increased. That's the general goal, though art shots may call for a more extreme approach.

This article has just touched upon the incredible range of tools available in the digital darkroom. There are many others -- Dodging & Burning, layer blending -- the list goes on. But I hope that now you are oriented and have an idea of a good processing sequence, you can add in other effects as your need (and knowledge) increases.



Anonymous said...

Nice Article!

Anonymous said...

Hi robin,
This is absolutely great article. Thank you for the hard work.

Gayathri Babu. G said...

Good and informative article...

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