Help - Picture quality

[S Mitra]

Hi,

A friend has been using 2 nos. Nikon S1 for the last 2 years. For quite some time, I have been noticing a problem in most of his photos from one camera. Now the other camera has also started exhibiting the same problem. I am not able to figure out the reason, any help would be welcome.

The midtones, instead of being different shades of one color, are made up of clusters of red and green patches. Why should green pixels show up in an area which is supposed to be brown skin tone ? Why should red pixels show up in areas which should be a grey - green wall ?

From Drop Box

The above is a lossless crop from one picture.

I have also noticed the same effect in photographs taken by mobile phone cameras. But there seems to be no clear correlation to image resolution or the jpeg compression ratio as far as I can see.

thanks in advance.

S Mitra

[wulf]

Have you got EXIF data for this shot? My guess is that the ISO setting was relatively high. Taking the same shot but turning down the ISO and compensating with aperture and / or shutter speed would make a difference.

However, that is a guess. It could be degradation of the sensor but check the ISO thing first.

Wulf

[S Mitra]

Here is a screenshot showing EXIF data.

From Drop Box

This shot is taken with max. ISO setting of 400.I will try out with a lower ISO.

[wulf]

Try several shots of the same subject (indoors, with artificial lighting, is most controllable) at a range of ISO settings. That will give you a useful set of pictures on which you can make fair comparisons.

Let us know how you get on.

Wulf

[fletch]

This looks like high ISO noise and a lot of P&S type camera do exhibit it at ISO 400 and above. Another candidate may be the JPEG quality setting. I would always leave it on fine but hey may have changed to medium or low quality.

[wulf]

It doesn't look to me like JPEG compression - that tends to be blocky when viewed close-up.

Wulf

[RoyL]

Photo has been taken in Normal (Auto mode). It has tried to shoot at 1/158 and ISO 400, with flash, which will produce a noisy image. Try Program mode at it seems to do a better job of Auto shots.

Otherwise stick it on Aperture Priority at f5.6, for a shot like this anyway. Set ISO to 100, and use Flash but Stopped down with a piece of tissue to diffuse the light.

Or, go Manual mode, shutter 1/250, aperture f5.6, ISO 100, and diffused flash.

Take your pick, any should work.

[kencaleno]

This is excessive chroma noise

To combat this in future images:

a) Have adequate lighting

b) Set camera for lowest ISO setting

c) Set camera for highest quality resolution


Regards, Ken