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1
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2
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3
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4
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5
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6
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- RGB is an additive color space.
- To make a pure color brighter, the other colors must be added to it.
- This inherently causes a loss of saturation.
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7
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- To help preserve color, one can reduce the opacity of the luminance
layer.
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8
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9
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- Reducing luminance opacity results in a loss of contrast.
- Is there a better solution?
- Why does the luminance layer desaturate the stars, but not extended
objects?
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10
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11
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- Usually we concentrate on the extended object when stretching the
histogram.
- It’s very easy to clip stellar profiles during this process.
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12
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- My preferred method.
- Nearly a “one stop shop” for histogram stretching.
- Tends to preserve stellar profiles while enhancing contrast in extended
objects.
- Background and mid-level can be tricky to set.
- Suggested: disable the sharpening aspect of DDP.
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13
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14
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15
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16
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- Contrast of luminance and color data must be maintained, or color will
be lost or distorted.
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17
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- First do an LRGB combine of the color data with the original luminance
data.
- Perhaps reduce the luminance weight to help retain saturation.
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18
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- Then DDP stretch the resulting color image.
- Use similar background and mid-level parameters as for the luminance
image (relative to the new color image).
- Perhaps use a slightly higher mid-level to help preserve saturation.
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19
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- Maybe bump up the saturation a bit.
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20
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- Now proceed to Photoshop for LLRGB layering.
- Combine the DDP-stretched luminance with the DDP-stretched LRGB data.
- Perhaps sharpening can be applied to the luminance layer.
- Of course, the true test of any idea is…
- DOES IT WORK?
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21
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22
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23
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- A combination of techniques may be needed.
- Each image seems to want a slightly different flow.
- The main point is to get an intuitive feel for what your processing does
to the data.
- And as always, never be afraid to…
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24
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Notes
