Thursday, December 23, 2004

 

In-camera sharpening

When I got my digital camera, I used to shoot pretty much in auto mode. Later when I became a bit experienced and started reading photography books/articles, I started shooting manual.

I knew enough about f-stops and shutter speeds and but I didn't know anything about some of the camera settings and I couldn't find anything on the web either. Even the camera manual was of no help. Like should I increase the color saturation using settings on the camera or should I use photoshop? What about contrast? What about sharpening? How do I know whether the camera does a better job than post-processing software.

The most confusing setting among these is the sharpening. Some people say that setting the in-camera sharpening to low or normal is actually good. While some folks are dead against using any kind of in-camera sharpening at all. After searching on the internet for many days and getting nowhere, I decided to try it for myself. One fact that adds to the confusion is that the in-camera sharpening is applied before the file is converted to jpeg.

I have an olympus C-760 UZ, a variation of which, C-765, is sold in the US. It has sharpening settings of -5 to +5, in +1 increments. As part of this test, I made three exposures, one at sharpening set to -5, one at 0, and one at a setting of +5. All these pictures were taken at the highest resolution of the camera and then cropped using iPhoto. No other editing of any kind was done. The photos were taken in low light to boost the effect of the noise. Otherwise it would be very difficult to do the comparison. Here is what I found:

Sharpening set to 0
This first exposure was made at a sharpening setting of -5. There is little noise in the shadows, especially under the big center leaf. There is some noise in the highlights too but it is not so bad. Also notice that the part of leaf visible in the lower left corner (the pointed one) has no apparent halos around it. It actually has a little but it's hardly visible.


Sharpening set to 0
This exposure was made at a sharpening setting of 0. Comparing it to the exposure at -5, the noise is much more visible all across the image. Also notice the halo around the leaf in the lower left corner. It is much more prominent now. This was the setting I used to shoot at and wonder where all that noise came from. In fact I did not know that the sharpening scale on my camera went from -5 to +5. I always used to think that 0 was the lowest until I read the manual. Well, that teaches me something.


Sharpening set to +5
This exposure was taken at +5 sharpening and clearly is the worst of the lot, but that was kind of expected.

After finding out what in-camera sharpening did to the photos, I wanted to find out But how much worse (or better??) was this than photoshop sharpening? I tried many settings in unsharp masking and found that in most of the cases, photoshop outperformed the camera. The only time when camera sharpening was better was when the amount was too high and the threshold was too low in photoshop USM. The camera just does not provide the level of control afforded by photoshop. Another reason to avoid in-camera sharpening is that it does not allow selective sharpening.


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