25% (~900x600) 33% (~1200x800) 50% (~1800x1200) .

Data - Information - Digital Proc. - Other pics

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Comparison with the final result

Scaneado with a Polaroid SprintScan 35 at 2700dpi, and processed with Pleiades PixInsight 1.0.0.50b. First I cropped one image (the black border), and aligned the rest of them related to the cropped one. Then I averaged all the images, and cropped the common area. You can see the integrated picture above.

Here is the result of applying an AV mask, using PI's DBE. After a histograms adjustement (black and white points), the result is clear.

A curves adjustement in each channel corrects the color balance.

Another curves adjustement changes the image's lightness and contrast, specially in the shadows.

Here a PIP transform was applied (similar to SMI, but less agressive). As you can see, it increased the contrast in the shadows, while the highlights were preserved.

Now is time to apply some routines to reduce the noise in the image.

Sin reducción v/s Wavelets -- Wavelets v/s Deconvolución --
Deconvolución v/s SGBNR_L -- SGBNR_L v/s SGBNR_ab
Sin reducción v/s SGBNR_ab
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First, the A Trous Wavelet transform removes the high-frecuency noise, mainly due the scanning process. The Deconvolution (Regularizated Richardson-Lucy), improves the faint star's appearence, while the bright ones are untouched, 'couse a luminance mask was used. The deconvoluton also reduces a bit the noise. Finally, SGBNR fights agains the large scale noise, mainly the film's grains, when applied to the Lab channels. The Lab mode separates the luminance and the chromatic information, allowing SGBNR to be more efficient in the noise remotion (and requires less fine tuning from the user).

Again, I made histograms and curves adjustements to recover the contrast, and to make use of the full dinamical range.

Here I changed the saturation of the blues using Adobe Photoshop 6.0.

Finally, back using PixInsight, I made another PIP transform, followed by a Curves adjustement, wich decreased the luminance of the Milky Way's stars and gived a more natural appearence.

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