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View Full Version : Puple fringe and Blown out Images ...?



kireeti
09-12-2007, 10:50 PM
Well...i am expecting a Canon S5 IS the next week probably...


Before i play with it .....i was just reading in this forum regarding Purple fringe and Blown out images in Canon S5 IS....:rolleyes:

Is there any specific way of reducing Purple fringe mainly.....?

And wht are the precautions to be taken to avoid Blown out images....?


Thanks

Bynx
09-12-2007, 11:16 PM
The purple fringe is caused when there are two very contrasting elements such as leaves or branches against a pure white sky. To reduce this keep contrast to a minimum. Otherwise, the purple can be fixed in Photoshop.

griptape
09-13-2007, 01:10 AM
What bynx said. Sensors only "see" black and gray (they see light rather than color), so at those intersections, the in camera computer ends up thinking that edge was actually purple.

And to avoid blown highlights... This is a tough one to explain in depth, but digital cameras can only reproduce a few different levels of light. If you have a dark forest, and a bright sky, the camera will either underexpose the forest to get the sky right, or overexpose the sky (blown highlights) to get the forest right. It's a matter of dynamic range (google HDR or high dynamic range to see workaround for this). Avoid shooting towards the sun, and keep things as low contrast as possible We're not talking about color here, we're talking about amount of light. Millions of hues of colors will turn out just fine if they're all lit the exact same, but one color with multiple shadows and different amounts of light become a problem.

Pave
09-13-2007, 03:40 AM
...And to avoid blown highlights... This is a tough one to explain in depth, but digital cameras can only reproduce a few different levels of light. If you have a dark forest, and a bright sky, the camera will either underexpose the forest to get the sky right, or overexpose the sky (blown highlights) to get the forest right...
You can always solve this either by using appropriate filter or by taking two different shots. One with properly exposed forest and one with properly expodes sky and then merging them in computer...

coldrain
09-13-2007, 03:47 AM
Purple fringing can be reduced by using a smaller aperture. Smaller aperture means less light on the sensor, which will mean less light to bounce back to create purple fringing.