how to add noise with noiselayer correctly?

pure · #1 02-17-2007, 12:24 PM

hi

i am about to put a person into a ready shot scene, its film and grainy in color. the grain is intended, and the new shot is digital and there is no grain.
so i built the person into the scene and added a layer above all person layers, selected the persons' alpha channel, filled it with white and used filter "add noise (b&w, gaussian) at 2 px, 3 times one after another – with blending mode "abblenden" (sorry how is that called in english?) and that made a nice grain over the person looking kind of real. its not 100% real so i would like to ask how to set the blending mode correctly.

i tried all blending possib., but there wasnt any nice than "abblenden" and also no better one (?)

when i visually analyze the original grain in the film scan at lets say 300% magnification or more, its also looking like noise, which i can reproduce with "add noise" filter but the noise has always the color the background is like. for example in the sky, the filmgrain is blueshaded and over skin its brown-beige shaded. my noise level is just a black grain and doesnt have the color the background or person has, if i add colornoise in the filteroption, the color is like a rainbow and doesnt look real, too.

any idea?
thanks

smiley guy · #2 02-17-2007, 01:33 PM

It sounds like you're doing everything just fine. I'm not sure what "abblenden" means but here's what I do for adding grain:

new layer
fill with 50% gray
set blending mode to "overlay"
run "add noise" filter to desired level (mine is usually around 4-5%)
run it again for more noise or delete and redo at higher % for more noise or reduce opacity for less noise or delete and redo at lower % for less noise

Sometimes when doing a restore I end up cleaning up with Noise Ninja but then add in grain again at the end to "cover my tracks" in a way. It helps to mask some traces of cloning etc. and gives a more consistent feel to the picture. Maybe instead of trying to match the grain that is already there, clean it up and add your own grain all over the picture. Just a thought.

pure · #3 02-17-2007, 03:17 PM

thats a very good idea with 50% grey
i try that, thanks

i just would like to see the noise in he same
color than the person at every pixel if possible.

sometimes i even do a gaussian blur at 0,2 px
with the noise as it is too harsh and edgy.
and repeat the noise adding with 2px. like you do.

removing noise from original background would be perfect
and adding then own noise, but in this special case i am not allowed
to touch the background, only at the parts where it touches the new person

thanks

smiley guy · #4 02-18-2007, 06:36 AM

Sorry, one step was missing in there and that was to make the noise "monochrome" or whatever the selection is so that it's not colour noise.

I don't mean to pry but is this a general thing where you are "not allowed to touch the background" or is that just the case for this picture? And I'm curious as to why, if I may be allowed to ask?

pure · #5 02-18-2007, 11:42 AM

yes i presumed you do it in monochrome. thanks again.

no its only a special thing with the whole background, its an ad
and the background is proofed in CMYK already, so if i change it i must proof it again and it has to look as the 1st proof....

pure · #6 02-18-2007, 12:59 PM

i tried this method with 50% grey, overlay, and noise.
the black parts of the image, in the hair and so on, are getting lightened with overlay, do you have a trick? i ll return to fill white again.

rmizell · #7 02-18-2007, 09:22 PM

Instead of running it on overlay, you can run it on "soft light" to keep it toned down a little. Another thing to do is just to mask it so only parts that really need grain are there. That way you can change the opacity of the brushes to adjust the amount of grain that is apparent.

smiley guy · #8 02-19-2007, 07:07 AM

Pure: I don't know what the problem would be with the darker parts of the hair getting lighter. Overlay blending mode shouldn't do that. I tried it on a couple of my images just to double check after you mentioned it and I don't see it happening. I don't see any shift in luminosity or colour, just the added grain/noise.

Hmmmmm... now you have me thinking.

pure · #9 02-22-2007, 03:07 AM

i dont know sorry. i am working in cmyk, maybe thats why?

so, actually i made it. it works great, maybe i should check this plugin which can reproduce film grain from any kodak or whatever filmgrain, photographers use. but then i also would need a blending method.
i tried both overlay and softlight with 50% grey filling, and it changed the luminance of the whole pic.

thanks

bart_hickman · #10 02-26-2007, 01:08 AM

Quote:

Originally Posted by smiley guy

Pure: I don't know what the problem would be with the darker parts of the hair getting lighter. Overlay blending mode shouldn't do that. I tried it on a couple of my images just to double check after you mentioned it and I don't see it happening. I don't see any shift in luminosity or colour, just the added grain/noise.

Hmmmmm... now you have me thinking.

I've noticed that the "50%" grey swatch in photoshop gives the RGB values of 149,149,149 (I have no idea why this is) and if one uses that, then overlay (and soft light, hard light, linear light) will brighten the image. In this case, 50% really means 128,128,128.

Bart

smiley guy · #11 02-26-2007, 07:34 AM

That is interesting... I'll have to check that out later. Colour checking by numbers and not by my eye! I don't notice any change but the numbers would indicate otherwise.

ikagami · #12 02-27-2007, 03:14 PM

Quote:

Originally Posted by pure

hi

i am about to put a person into a ready shot scene, its film and grainy in color. the grain is intended, and the new shot is digital and there is no grain.
so i built the person into the scene and added a layer above all person layers, selected the persons' alpha channel, filled it with white and used filter "add noise (b&w, gaussian) at 2 px, 3 times one after another – with blending mode "abblenden" (sorry how is that called in english?) and that made a nice grain over the person looking kind of real. its not 100% real so i would like to ask how to set the blending mode correctly.

i tried all blending possib., but there wasnt any nice than "abblenden" and also no better one (?)

when i visually analyze the original grain in the film scan at lets say 300% magnification or more, its also looking like noise, which i can reproduce with "add noise" filter but the noise has always the color the background is like. for example in the sky, the filmgrain is blueshaded and over skin its brown-beige shaded. my noise level is just a black grain and doesnt have the color the background or person has, if i add colornoise in the filteroption, the color is like a rainbow and doesnt look real, too.

any idea?
thanks

try to get the same film and have it developed so you get a blank strip
have this scanned and use the overlay option to bring in only the filmgrain...