jonnyboy Posted September 19, 2006 Share Posted September 19, 2006 what exactly is luminance when using LRGB filter. any reply would be grateful.cheers guys Link to comment Share on other sites More sharing options...
GordonCopestake Posted September 19, 2006 Share Posted September 19, 2006 Brightness? Link to comment Share on other sites More sharing options...
CELESCOPE Posted September 19, 2006 Share Posted September 19, 2006 Hi Luminance is unfiltered light . need a high signal to noise Ratio, rgb filters usually are binned 2x2 for sensitivity, i never use the lum filter mainly because of the LP where i live , so i use an Ha filter instead of the LUM , . this would be for capturing DSOs, for galaxies i would use the CLS filter for the lum part . hope that helps Rog Link to comment Share on other sites More sharing options...
Astroman Posted September 19, 2006 Share Posted September 19, 2006 When using standard LRGB filters with a CCD camera, the image is actually taken in black and white through the filter. The colors are assigned by the software later. A "luminance" image is just the black and white image, or greyscale if you like. So brightness is fairly correct. Link to comment Share on other sites More sharing options...
MartinB Posted September 19, 2006 Share Posted September 19, 2006 The reason for adding a plain B+W layer to the image is to provide fine detail. The eye is much more sensitive to fine detail in B+W images than colour, so the fine detail of an LRGB is provided by the luminence layer. When combining layers it is quite common to blur the colour layers to reduce noise and sharpen the luminence. I tend to use a CLS filter but as Rog says you can also use Ha very effectively on emission nebulae. You don't actually need to filter the luminence layer at all. Link to comment Share on other sites More sharing options...
jonnyboy Posted September 20, 2006 Author Share Posted September 20, 2006 thank for your replies they makes more sense than the books i have they mainly just give you the time they have used for each filter.cheers jon Link to comment Share on other sites More sharing options...
Astroman Posted September 20, 2006 Share Posted September 20, 2006 Well said, Martin. Link to comment Share on other sites More sharing options...
FLO Posted September 20, 2006 Share Posted September 20, 2006 ... the fine detail of an LRGB is provided by the luminence layer. Which is why it is better to apply sharpening to the luminance layer only... Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.