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AnswerRe: automatic byte conversion? Pin
Luc Pattyn8-May-09 12:06
sitebuilderLuc Pattyn8-May-09 12:06 
GeneralRe: automatic byte conversion? Pin
terradtc8-May-09 12:31
terradtc8-May-09 12:31 
GeneralRe: automatic byte conversion? Pin
Luc Pattyn8-May-09 12:44
sitebuilderLuc Pattyn8-May-09 12:44 
GeneralRe: automatic byte conversion? Pin
terradtc8-May-09 13:05
terradtc8-May-09 13:05 
GeneralRe: automatic byte conversion? Pin
Luc Pattyn8-May-09 13:25
sitebuilderLuc Pattyn8-May-09 13:25 
Questionreading pixel's value in an image Pin
wasifmuneer8-May-09 8:53
wasifmuneer8-May-09 8:53 
AnswerRe: reading pixel's value in an image Pin
molesworth8-May-09 9:05
molesworth8-May-09 9:05 
GeneralRe: reading pixel's value in an image Pin
Dan Neely8-May-09 9:27
Dan Neely8-May-09 9:27 
molesworth wrote:
It may not be as simple as that. A lot will depend on the quality of your images, and what was used to produce them, and a star will generally not be a simple area of pixels of the same value.


Unless the image is in single bit depth, or heavily processed it won't be.


Raw images in prosumer astronomy cameras are 12/16bit color depth, and since typical pixels are sized to have a capacity of between 40-100k electrons sampling noise is a factor in addition to the quantum noise of the chip itself.


Even ignoring noise, unless a star is perfectly centered on the corner between 4 pixels; and the pixels are large enough that all of the diffraction rings are completely on those 4 pixels; and the camera is anti-bloom* or the pixels aren't saturated; or the camera is non anti-bloom and you're only interested in IDing the middle of stars that have bloomed.




* normal daylight use cameras have a gap between each pixel on the sensor to keep them from blooming, this results in roughly 50% of the light falling on dead parts of the chip. For taking images of bright objects this doesn't matter (daylight, moon, planets), but doubles your exposure time for everything else. As a result most astrocams use chips that can bloom and require the user to combine multiple short exposures in post-processing. For most purposes this works better, the only exceptions being trying to image a very faint object next to a very bright one (eg the flame nebula (background for the horsehead)).

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AnswerRe: reading pixel's value in an image Pin
Dave Kreskowiak8-May-09 9:14
mveDave Kreskowiak8-May-09 9:14 
AnswerRe: reading pixel's value in an image Pin
terradtc8-May-09 10:50
terradtc8-May-09 10:50 
GeneralRe: reading pixel's value in an image Pin
wasifmuneer8-May-09 12:28
wasifmuneer8-May-09 12:28 
GeneralRe: reading pixel's value in an image Pin
Christian Graus8-May-09 14:53
protectorChristian Graus8-May-09 14:53 
GeneralRe: reading pixel's value in an image [modified] Pin
terradtc9-May-09 0:40
terradtc9-May-09 0:40 
Questionmsgbox show for a set time Pin
Sokka938-May-09 8:48
Sokka938-May-09 8:48 
AnswerRe: msgbox show for a set time Pin
Dave Kreskowiak8-May-09 9:00
mveDave Kreskowiak8-May-09 9:00 
AnswerRe: msgbox show for a set time Pin
Ravi Bhavnani8-May-09 11:31
professionalRavi Bhavnani8-May-09 11:31 
AnswerRe: msgbox show for a set time Pin
Atif Shahbaz8-May-09 21:05
Atif Shahbaz8-May-09 21:05 
AnswerRe: msgbox show for a set time Pin
Rajdeep.NET is BACK8-May-09 21:32
Rajdeep.NET is BACK8-May-09 21:32 
GeneralRe: msgbox show for a set time Pin
Sokka938-May-09 22:43
Sokka938-May-09 22:43 
QuestionSearching randomly Pin
Rajdeep.NET is BACK8-May-09 8:39
Rajdeep.NET is BACK8-May-09 8:39 
AnswerRe: Searching randomly Pin
fly9048-May-09 9:02
fly9048-May-09 9:02 
GeneralRe: Searching randomly Pin
Luc Pattyn8-May-09 9:17
sitebuilderLuc Pattyn8-May-09 9:17 
GeneralRe: Searching randomly Pin
fly9048-May-09 9:23
fly9048-May-09 9:23 
GeneralRe: Searching randomly Pin
Luc Pattyn8-May-09 9:39
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GeneralRe: Searching randomly Pin
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