Re: Question about "half-size" and "bin 2x2" commands


Dec 3, 2004

 


----------------------------

#15089 Dec 3, 2004

I have a SBIG 2000XCM camera and have a question about converting a a

one-shot CCD 1x1 binned color image to a 2x2 binned color image. Is

it posible to convert the 1x1 binned image to a 2x2 binned image and

thereby increase the brightness of the image similar to a 2x2 binned

image captured by the camera? Manual suggests that the 2x2 binned

command converts a 1x1 image to a 2x2 image and using the Pixel Math

command one can gain the benefits of a brighter 2x2 binned image. Is

this true? Also, the manual stated that half-size command could also

do this? Any help would be appreciated.



Thanks

James



----------------------------

#15113 Dec 6, 2004

James,



Yes you can "software bin" an image using the Bin 2x2 command. Note

that, unlike "analog" binning in a CCD camera, this does not reduce the

read noise contribution. But otherwise it has the same effect as binning.



The half-size command performs a decimate-and-filter algorithm, to

prevent aliasing. It is based on the method dictated by the Nyquist

sampling criterion. The results will be very slightly "blurrier" than

straight binning, but the image will not contain artifacts either.



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



---------------





jiprovi wrote: >

> I have a SBIG 2000XCM camera and have a question about converting a a

> one-shot CCD 1x1 binned color image to a 2x2 binned color image. Is

> it posible to convert the 1x1 binned image to a 2x2 binned image and

> thereby increase the brightness of the image similar to a 2x2 binned

> image captured by the camera? Manual suggests that the 2x2 binned

> command converts a 1x1 image to a 2x2 image and using the Pixel Math

> command one can gain the benefits of a brighter 2x2 binned image. Is

> this true? Also, the manual stated that half-size command could also

> do this? Any help would be appreciated.

>

> Thanks

> James



----------------------------

#15121 Dec 6, 2004

Doug - thanks for clarifying. The manual mentions I need to use pixel

math as the last step. Is this true and if so what is the percentage

- 400%?



thanks

James

--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@c...> wrote:

> James,

>

> Yes you can "software bin" an image using the Bin 2x2 command. Note

> that, unlike "analog" binning in a CCD camera, this does not reduce the

> read noise contribution. But otherwise it has the same effect as

binning.

>

> The half-size command performs a decimate-and-filter algorithm, to

> prevent aliasing. It is based on the method dictated by the Nyquist

> sampling criterion. The results will be very slightly "blurrier" than

> straight binning, but the image will not contain artifacts either.

>

> Doug

>

---------------

>

> Doug George

> dgeorge@c...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

---------------

>

>

> jiprovi wrote:

> >

> > I have a SBIG 2000XCM camera and have a question about converting a a

> > one-shot CCD 1x1 binned color image to a 2x2 binned color image. Is

> > it posible to convert the 1x1 binned image to a 2x2 binned image and

> > thereby increase the brightness of the image similar to a 2x2 binned

> > image captured by the camera? Manual suggests that the 2x2 binned

> > command converts a 1x1 image to a 2x2 image and using the Pixel Math

> > command one can gain the benefits of a brighter 2x2 binned image. Is

> > this true? Also, the manual stated that half-size command could also

> > do this? Any help would be appreciated.

> >

> > Thanks

> > James



----------------------------

#15127 Dec 7, 2004

jiprovi wrote: >

> Doug - thanks for clarifying. The manual mentions I need to use pixel

> math as the last step. Is this true and if so what is the percentage

> - 400%?



It depends on what you are trying to achieve. If you need to keep the

Photoelectrons per ADU (gain) the same, then yes you need to scale it

up. The Bin 2x2 command does an average operation instead of a sum

operation, like a camera would internally. However, scaling it up will

increase the dynamic range beyond 65535, so it may be an problem if you

want to save the image in a 16-bit file format.



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



---------------







----------------------------

#15133 Dec 7, 2004

Doug, thanks - I was trying to keep the photoelectron/ADU the same so to emulate more

of what the camera was doing. Also, thanks for the heads-up regarding danger of

exceeding the 65535 range.



Thanks,

James

--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@c...> wrote:

> jiprovi wrote:

> >

> > Doug - thanks for clarifying. The manual mentions I need to use pixel

> > math as the last step. Is this true and if so what is the percentage

> > - 400%?

>

> It depends on what you are trying to achieve. If you need to keep the

> Photoelectrons per ADU (gain) the same, then yes you need to scale it

> up. The Bin 2x2 command does an average operation instead of a sum

> operation, like a camera would internally. However, scaling it up will

> increase the dynamic range beyond 65535, so it may be an problem if you

> want to save the image in a 16-bit file format.

>

> Doug

>

---------------

>

> Doug George

> dgeorge@c...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

---------------



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