Resolution/ISO

Hey If you manually reduce the resolution on your SLR will it improve noise results at high ISO?

Anyone use this to get better results?
Is the trade off worth it?

melekalikimaka

blindjustice wrote: »

Hey If you manually reduce the resolution on your SLR will it improve noise results at high ISO?

Anyone use this to get better results?
Is the trade off worth it?

it might have a small effect in theory... wouldnt be worth it... I doubt it has any effect tbh...

mdebets

Is reducing the resolution actually switches off pixels on the sensor, or is it just an after processing step, with the capturing done with the original number of pixels.
In the first case, it should lead to some improvement, as you have a lower pixel density, but in the second case, it should bring no improvement.

melekalikimaka

mdebets wrote: »

Is reducing the resolution actually switches off pixels on the sensor, or is it just an after processing step, with the capturing done with the original number of pixels.
In the first case, it should lead to some improvement, as you have a lower pixel density, but in the second case, it should bring no improvement.

aye, what are you shooting that requires you to drop the res in favour of less noise? its a nasty trade off

mdebets

melekalikimaka wrote: »

aye, what are you shooting that requires you to drop the res in favour of less noise? its a nasty trade off

I'm not the OP, so I'm not doing this,. I was just courious what actually happens, when you drop resolution, which would determine, if noise levels would stay the same or would improve.

melekalikimaka

mdebets wrote: »

I'm not the OP, so I'm not doing this,. I was just courious what actually happens, when you drop resolution, which would determine, if noise levels would stay the same or would improve.

noise is caused my electrical interference between the pixel sensors being close, so my reducing the res, perhaps there is less sensor points being used, ie spacer further apart, in turn reducing interference, causing less noise

charybdis

Not really.

When you specify a smaller resolution on your camera it just changes the JPEG output resolution, it doesn't affect anything besides output file processing. The camera still caputres the full sensor's worth of data as normal.

You may see what appears to be increased noise performance, but what you're really seeing is less spatial information which makes the noise look smoother, it's similar to how thumbnails of images often look sharper than a full-sized image.

There are reasons to use your camera to produce smaller JPEGs, but high-ISO noise reduction probably isn't one of them unless you know exactly what your output medium is and don't want to process the files yourself.

mdebets

melekalikimaka wrote: »

noise is caused my electrical interference between the pixel sensors being close, so my reducing the res, perhaps there is less sensor points being used, ie spacer further apart, in turn reducing interference, causing less noise

I know that, hence my question.
1) if a resoultion dropm means less pixels used then you have less noise, because of a wider spacing in the pixels.
2) if a resolution drop just means that the original picture is downscaled by software in the camera after it was taken, then you have the same noise, as the spacing of the original pixels is still the same.

if 1) is the case, it might be interesting to try it, if you realy have to use high ISO and don't intend to print the picture too big.

melekalikimaka

mdebets wrote: »

I know that, hence my question.
1) if a resoultion dropm means less pixels used then you have less noise, because of a wider spacing in the pixels.

in theory yes

mdebets wrote: »

2) if a resolution drop just means that the original picture is downscaled by software in the camera after it was taken, then you have the same noise, as the spacing of the original pixels is still the same.

if 1) is the case, it might be interesting to try it, if you realy have to use high ISO and don't intend to print the picture too big.

dont think its done by software, in nikons shooting in dx model uses the center of the sensor to prevent vignetting. so i assume it doesnt space them out, maybe it just notches away at the border to lower mp.

Heebie

Fuji cameras (at least earlier models.. don't know about the current line) like the 7600 (which I own) actually uses an algorithm to come up with a lower-resolution, lower-noise picture. (You're limited to 2MP on a 6MP camera) when you're using low ISO. (It goes down to 800.. normally does 200 & 400)

so.. there might be algorithms in-place in the post-processing that either ignore pixels, or use some other method to try & compensate for noise.

I would think, however, that it would be mentioned in the documentation for the camera if this were the case.

melekalikimaka

Heebie wrote: »

Fuji cameras (at least earlier models.. don't know about the current line) like the 7600 (which I own) actually uses an algorithm to come up with a lower-resolution, lower-noise picture. (You're limited to 2MP on a 6MP camera) when you're using low ISO. (It goes down to 800.. normally does 200 & 400)

so.. there might be algorithms in-place in the post-processing that either ignore pixels, or use some other method to try & compensate for noise.

I would think, however, that it would be mentioned in the documentation for the camera if this were the case.

Chroma and luminance noise separation is the best method at the mo from what i gather, the rest just soften the image to blend the noise(i could be wayyyy off here tho)

Heebie

Some of Fuji's image sensors (the Super CCD SR line) actually filter out chroma and luma at the image-sensor level. (They have separate chroma and luma sensors.. each octagonal chroma sensor has an embedded, but electrically separate, luma sensor.. it's pretty sweet.)

melekalikimaka wrote: »

Chroma and luminance noise separation is the best method at the mo from what i gather, the rest just soften the image to blend the noise(i could be wayyyy off here tho)

melekalikimaka

http://www.dxomark.com/index.php/eng/DxOMark-Sensor

fuji lost the edge somewhere...

charybdis

mdebets wrote: »

1) if a resoultion dropm means less pixels used then you have less noise, because of a wider spacing in the pixels.

No, although some esoteric Fuji sensors do something not entirely unlike what you're describing.

mdebets wrote: »

2) if a resolution drop just means that the original picture is downscaled by software in the camera after it was taken, then you have the same noise, as the spacing of the original pixels is still the same.

Yes.

Heebie wrote: »

Some of Fuji's image sensors (the Super CCD SR line) actually filter out chroma and luma at the image-sensor level. (They have separate chroma and luma sensors.. each octagonal chroma sensor has an embedded, but electrically separate, luma sensor.. it's pretty sweet.)

I don't think that's the case.

As far as I can tell, the Super CCD SR line of sensors have 2 photosites per bayer cell of different luminance sensitivities, but because they're both under the same coloured bayer cell, they record similar chrominance information. This effectively means that chroma subsampling (or something very similar) is happening at the sensor and early processing level (I think). This results in extended dynamic range because of the combination of two discrete sets of luminance information, but doesn't necessarily result in better high ISO performance.

If I'm wrong I'd be very interested to hear how so.