FFT Question

[Kymme]

Sorry, this will probably rate as "dumb question of the week" - but here goes anyway. I followed the tutorial on FFT here - which was great by the way but I'm obviously being thick.

So, just some clarification on three stages of the process if someone doesn't mind.....

1) Make a grayscale image (FFT doesn't work with color)
I assume this means desaturate or something because it doesn't seem to come up on photoshop as a filter at all if you're in greyscale - or am I missing something really obvious?

2) Make a duplicate merged copy (FFT sometimes seems to get lost with layers)
Is that make another merged layer or, as I suspect, work off a copy of the file?


5) On the Blue channel, clone out the stars with blending set do Darken, on the Green channel clone using Lighten. Do not touch the middle part, just the little stars. Do not touch the Red channel
Here is where I get totally lost - which stars am I meant to clone out????. I have attached a picture of what I get on the blue and green channels. Do you mean all the little white dots on the blue channel or the star bit in the middle? Confused cause it said don't touch the middle.

Thanks
Kymme

[Duv]

Hi Kymme. Merry Christmas! By the way, there are no dumb questions in this forum and FFT is not the easiest tool to use or understand. Roland's method may be best but generally I keep it simple.

Image: Duplicate
Image: Adjustments: Greyscale
Run FFT (I seem to get acceptable results just running in RGB mode and I've never had the need to run the filter on individual channels)
Clone out the "stars". Well some may look like stars, others smudges. Look for white discoloration in the "noise". In your image it looks like some at the top and bottom plus one at 10 o'clock and 4 o'clock from the centre. Sometimes if you zoom in you can better see the white markings. Don't touch the centre star.
Run IFFT
Shift-drag onto original image and change to Luminosity.
Let me know if you have any questions.

Cheers
Dave

[Kymme]

Thanks for that, now it makes more sense. I assume if there are no small stars then there is not a regular texture to remove - seems that way. Its a great tool by the way - love this filter!!!!