Images below show a 23°×34° wide field view of constellation Orion which is rich of nebulae. Descriptions can be found below the images. Image and instrument data can be found at the end of this page.
Full resolution (31 MB):
Half resolution (8.4 MB):
This visualization is a false color image where H-alpha (including red continuum) is mapped to red, blue continuum is mapped to green and red continuum (without H-alpha) is mapped to blue, i.e. H-alpha emission nebulae are shown red and reflection nebulae appear blue to green.
Stars in the continuum channels are partially subtracted in order to make the faint reflection nebulae visible. Further image processing steps are dynamic range compression using a nonlinear hi-pass filter and tonal curve correction.
Full resolution (34 MB):
Half resolution (7.3 MB):
This visualization is a false color image which only uses the H-alpha data (including some red continuum). It shows much more details of the emission nebulae then the image above.
After partial star subtraction the dynamic range was compressed using a non-linear hi-pass filter. That leads to a compression ratio r which is used to calculate the color as depicted in the legend. (The legend shows the compression values c:=1-r). The luminance is determined by the tonal curve corrected result of the dynamic range compression.
Half resolution (10.4 MB):
This image comes close to a true color view. Red contains red continuum including some (but reduced) H-alpha, Green continuum is mapped to green and blue continuum is mapped to blue.
Unlike to the other images the stars are not subtracted. This makes the dark nebulae visible, because they cover the light from the stars behind.
The only image processing steps after color composition are dynamic range compression using a nonlinear hi-pass filter and tonal curve correction.
Due to the limited resolution of the continuum data that image is only presented at half resolution.
It should be noted that all image processing steps are deterministic, i.e. there is no manual retouching or any kind of non-reproducible adjustment.
Image data are:
|Center position:||RA: 5h30, DEC: 1°|
|Orientation:||North is up (exactly)|
|Scale:||10 arcsec/pixel (in center at full resolution)|
|Dimensions:||23°×34° (through center)|
|Exposure times:||H-alpha: 7.4d, continuum channels: 5.7d (sum of exposure times of all frames used to calculate the image)|
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