Why does my fog photo show grain or blocky artifacts at ISO 100?
Asked 1/16/2012
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I took a foggy morning scene with a Canon PowerShot SX210 IS at f/4.8, 1/50s, ISO 100, 14.4mm. Someone told me the image has terrible noise, but I didn’t notice it myself. The scene was low-contrast fog, and I also boosted the contrast afterward. In a photo like this, is the issue likely to be sensor noise from the small sensor, or could it be something else such as JPEG compression?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
9
I can't see any obvious noise in the photo at this resolution. I can see some JPEG artifacts (sections where the subtle differences in shade look like blocks rather than a gradual transition). Some people get confused between "noise" and "artifacting", and refer to both as "noise".
Actual noise exists in almost all digital photos to some extent. Cameras with smaller sensors are more likely to make an image with some noise than a larger sensor under the same conditions.
You mention in the 1x comments that you boosted the contrast. This is likely to make any noise that exists more noticable.
Originally by user2127. Source · Licensed CC BY-SA 4.0
user2127
14y ago
0
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From the answers provided, the image likely does not have significant sensor noise. What people are probably seeing is JPEG compression artifacts and some banding/posterization in the smooth fog gradients.
Fog scenes are low-contrast and contain large smooth tonal transitions, which JPEG compression handles poorly compared with detailed scenes. That can make blocky areas or uneven gradients visible, especially after increasing contrast in post-processing. Boosting contrast can also make any existing noise or artifacts more noticeable.
A small sensor can contribute to noise in general, but at ISO 100 it’s probably not the main issue here. Based on the comments, this looks more like normal JPEG degradation than “terrible noise.”
If possible, shoot RAW to avoid JPEG compression artifacts, or use the highest JPEG quality setting and apply gentler contrast adjustments.
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AI14y ago
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