Minimum filter use a problem.

[Hagar (Doug)]

I am having a problem using the minimum filter in Photoshop to reduce stars in my recent images. The min pixel size for this filter is 1 Pixel. Using this setting removes almost all stars from the image and leaves it quite pixelated.

I suspect it has something to do with image scale or resolution. Is there anything I can do?

Equipment used:
Telescope:
Takahashi FSQ106ED at F5
Appature: 106mm
Focal length: 530mm

Camera:
QHY8 cooled OSC
Sony ICX-453
Total pixel : 3110 x 2030
Active pixels: 3032 x 2016
Pixel Size: 7.8um x 7.8um square
Color method: RGB BAYER film on CCD
Effective sensor area: 28.4 mm diagonal
Readout noise: 8 -12 e @600Kpixel/s
QE: 60% at Green (Peak) , 50% at Blue and H.a
Microlensing on chip
Progressive Scan
NABG: -110dB

[multiweb (Marc)]

Upsize your image 200% or more then use the filter on upsampled pic then reduce back to original size. You can do this as part of your processing for fine details as well.

[Octane (Humayun)]

Doug,

I wouldn't worry too much about even using the minimum filter. I'm a bit old skool in my thinking with regards to filters such as those. I can't help but feel that they're destructive to both the image and the data.

Regards,
Humayun

[multiweb (Marc)]

Originally Posted by Octane

Doug,

I wouldn't worry too much about even using the minimum filter. I'm a bit old skool in my thinking with regards to filters such as those. I can't help but feel that they're destructive to both the image and the data.

Regards,
Humayun

Totally agree. I though Doug wanted to do the stars tighter only. I would only use this filter on an isolated star selection. Minimum filter is nasty on any other data but to me stars are just soft coloured discs. They can take a fair bit of beating. The neb parts are better worked on with a light deconvolution on the raw, then selective sharpening in PS.

[[1ponders] (Paul)]

Doug, immediately after applying the minimum filter got Edit>fade minimum and adjust the slider to achieve the result you want. Edit>fade is fantastic for use immediately after any filter application to fine tune it. It must be used immediately after though.

[sheeny (Al)]

Originally Posted by [1ponders]

Doug, immediately after applying the minimum filter got Edit>fade minimum and adjust the slider to achieve the result you want. Edit>fade is fantastic for use immediately after any filter application to fine tune it. It must be used immediately after though.

Good tip, Paul. I had not come across Edit> Fade before.

Al.

[[1ponders] (Paul)]

Also Al if you have the Carboni Action try using the "...As layer on Top" action after doing another action. You can then use the opacity or blending options then to fine tune the original actions which can sometimes be a bit much. It doesn't work on all the actions but it does on many of them.

[Hagar (Doug)]

Thank you so much Paul, That is exactly what I was after. Now I can reduce the overpowering star field quite easily without totally destroying the entire image.

Thaks everyone else as well. Great we can share hints and tips. This problem was a big one for me as the wider field images can be somewhat cluttered.

Originally Posted by [1ponders]

Doug, immediately after applying the minimum filter got Edit>fade minimum and adjust the slider to achieve the result you want. Edit>fade is fantastic for use immediately after any filter application to fine tune it. It must be used immediately after though.

[sheeny (Al)]

Originally Posted by [1ponders]

Also Al if you have the Carboni Action try using the "...As layer on Top" action after doing another action. You can then use the opacity or blending options then to fine tune the original actions which can sometimes be a bit much. It doesn't work on all the actions but it does on many of them.

I don't have any actions, Paul. Where can I get that?

Al.

[[1ponders] (Paul)]

Right here Al
http://actions.home.att.net/Astronomy_Tools.html

[sheeny (Al)]

Paul.

Al.