Noise reduction

When it comes to sharpening I use a 2 stage process: capture sharpening in Silkypix, then USM after downsizing to JPEG. Sometimes I do the downsizing and USM in PS Elements if I have done selective editing on the image.

My question is: when is the best time to apply Noise reduction ? :

1. while the image is still full size, ie in silkypix or PSE before downsizing OR

2. After downsizing ?

I can't see how any post-processing is going to add noise, so I would remove it as early as possible. And since Silkypix will probably do a better job than most other software, that would seem to be the perfect time.

G

Noise reduction is best done before sharpening, then there there is less noise that is sharpened ("brung out"). But that's not relevant when using Silkypix for both because Silkypix does does the processing in the optimum order for you automatically. Everything is redone from scratch when you go to save the image, or "develop" as they call it.

If any other program is preferable for noise reduction than Silkypix, I would create a full size TIFF from Silkypix for further processing rather than resizing. Otherwise the results will be cruder as the program will have less detail to work with.

Sharpening is usually the last step in the process. It introduces artifacts, so you don't want to further compound the degradation by further processing after sharpening.

These days I make an A3 of any image I process and save it unsharpened. I then do the final sharpening before printing, or after reducing in size for web, depending on the final use. In this way I could also make different sizes of print and sharpen each size in a more appropriate way.

In Silkypix

I use Silkypix for noise reduction using MattMatics guidelines. See my post "High ISO" in Your Photos Forum. Thanks Matt.

ok thanks for the replies. In Silkypix I get no option to choose whether I am applying NR BEFORE or AFTER downsizing. That is fine as I am happy to let Silkypix do what it thinks is best.

But say I have a full size TIFF that has had no NR applied to it. I open it in Photoshop Elements and want to apply NR and downsize it to 800x800pixels.

Would it be best to apply NR at full size,then downsize the image.

OR Downsize the image first, and then apply NR.

I will try and shoot some noisy images and do some tests myself, but would be interested to hear others views first.

Noise is mostly only one pixel so if you down size it you will spread it over to other pixels in a sence so better reduce it before you downsizing.
Atleast that's my view on it.

edit: typo

As a side effect, noise reduction reduces normal proper detail in your images somewhat as well as noise. This will happen to a greater extent if you downsize before applying NR.

I am not sure I agree with that. The more pixels you have to work with, the smaller the proportion that you need to change.

G

I suspect we agree with each other but are not understanding each other.

I mean it's better to apply NR before resizing. Which way round do you think is best?