Making Spectacular "Truecolor" Images of the Sun

[t00fri]

Hi all,

after julesstoops great pointer to the very recent
/simulataneous/ multichannel solar images from
DOT (Dutch Open Telescope),

http://dot.astro.uu.nl

I could not resist extracting AND color-composing some
shown very hires solar grayscale images. After careful
alignment with GIMP, the result is a single super-hires RGB
"Truecolor" image.

The images have been taken /simultaneously/ through
appropriate, extremely narrowband R,G,B filters.

Let me share the spectacular result of this exercise with you
. The original image sizes were huge 3077x3077 pixels!

I now reduced the composite RGB image to 1000x1000 but
show you below three further detail views in the original
resolution. You can think of the solar "background" being
extremely reduced in illumination to some dark gray. Then
you see the red glows around the sunspot with all those
amazing details and subtle different color shades.

Let's look at the images NOW,

Bye Fridger

First the FULL view reduced to 1000x1000 pixels


Next 3 detail views in the original resolution (3077x3077)

[PlutonianEmpire]

So, the actual color of the sun is actually a bluish-grey or something like that?

[Hunter Parasite]

Wow. we've been stareing at a seemingly yellow ball in the sky. But it turns out be gray.

[t00fri]

Wow. we've been stareing at a seemingly yellow ball in the
sky. But it turns out be gray.

Not surprisingly, you didn't understand what was going on...

Computer monitors and also photographic images only
have a VERY small range of displaying light intensity.

So one has to interpret the above images as follows:

The solar background is dimmed by a huge factor
from a bright white glare to some neutral dark
gray. I hope that everyone realizes that this dimming
does NOT affect the colors, only their LUMINANCE.
The [R,G,B] representation of white is [255,255,255],
black is [0,0,0] and all neutral shades of grays are
in-between with a form [x,x,x], i.e. all three entries being
equal!

What you see is relative to that, of course.
It's like watching the sun with extremely dark gray sun
glasses . If the luminance was not dimmed so much,
we could see NOTHING but WHITE glare, which is not what
we want. The somewhat bluish tint is an artefact
(depending also on the used monitor) . It should really be
a neutral gray. It is a neutral gray on my TFT screen.

These delicate solar patterns can only be seen if --from the
wide spectrum of visible solar light-- we only allow
extremely narrow "slices" corresponding to the emission of
single atomic lines with line width < 0.0000000001
meters to reach our instruments!

Bye Fridger

[julesstoop]

They are great Fridger!
You really get a sense of the large scale structures in the photosphere, at least it seems like that.
I might try to do something similar with the four-part movies from the same site (given I find the time).

[ElChristou]

Truly amazing... no way to create a new highres alternative map using this work?

[jdou]

The Sun view at 656.3 nm H-alpha is very impressive

[Michael Kilderry]

I think the images make the sun look like a big lava ball, the red bits being the red hot glowing bits and the grey bits being the cooler and non-glowing parts.

It has commonly been said that the sun has a yellowish tinge, but in this image the sun looks grey and red, so does the sun have a slight yellow hue? Or is it just the blackbody colour or something?

[MackTuesday]

Where did you find the green images, t00fri? I found a table of filters that DOT uses on the "DOT Tomography" page -- filters in violet, blue, and red -- but nowhere on the site could I find any references to filters in the 500-565 nm range.

[t00fri]

Where did you find the green images, t00fri? I found a table of filters that DOT uses on the "DOT Tomography" page -- filters in violet, blue, and red -- but nowhere on the site could I find any references to filters in the 500-565 nm range.

Here:

RGB-sun

[MackTuesday]

>Here:

>RGB-sun

Are you sure that's where you got it? There's no green-filtered layer on that page.

[t00fri]

>Here:

>RGB-sun

Are you sure that's where you got it? There's no green-filtered layer on that page.

Yes, I must admit that I cheated a bit here: I "wavelength-shifted" the CaII and G-Band data into blue and green, respectively, by using a "software filter".

Bye Fridger