Helpful Posts: 0
14th April 2008, 06:41 AM
Can I use image averaging to reduce noise in hand-held photos?
One of the things bugging me in photography is...noise!! Aaargh.
Do I understand the image averaging technique correctly...?
You take 4 photos of the same scene.
Because of the random character of some noises, you can put these on top of each other in, for example, Photoshop by the way shown in the tutorial on this site.
I can take 4 'identical' photos when the camera is mounted on a tripod.
But what if I were to take a normal picture, shot with the camera being handheld?
I can not take more identical images.
Is there a way of averaging those images too?
I use a Canon 20D and shot many travel pics without a tripod.
In some cases I have to go as high as ISO 1600 which means NOISE!
Converting them to grey of sepia will reduce the feel of the noise and the noise is then less of a problem.
In color photos, I put two layers on top of each other and use in the upper photo the median filter, but selective. At some places it is not helpful, so using a layer mask, I brush it away.
Is there a better or other method for me?
14th April 2008, 06:47 AM
It is generally not recommended to try averaging photos taken hand-held since there will always be a significant amount of misalignment.
One thing that you could try, if you are willing to spend *lots* more time, is to manually align (aka register) all images taken in Photoshop. To do this accurately, use the "difference" blending method in photoshop to quickly see when they are in alignment. I recommend first upsizing the images to maybe 2-4x their original resolution in order to align with sub-pixel accuracy (since photoshop only allows nudging images in increments of one pixel). This can achieve ok (but inferior) results if done properly (although it is significantly more time-consuming and processor/memory intensive). Resolution will certainly suffer. You will undoubtedly also have to crop out the edges of the final image, and this amount of cropping will increase the more each photo moves relative to the others in the hand-held average composite. Of course, there can also be no subject movement.
If you already have the images and are just trying to use the sequence to improve quality, give it a try and see how it goes. Otherwise, just use a tripod next time...it is much much easier
14th April 2008, 06:49 AM
I'll try that.
Especially since the camera was in multi-image mode, it should be possible.