Clouds

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Don B. Cilly
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Clouds

Post by Don B. Cilly » 2019-07-12T23:32:03-07:00

Hope it's not a bad moment ;·)
I would like to know whether it's possible (actually, I'm sure it is, but...) to convert a "cloud" image to... well, not quite lower resolution - that's easy - but lower "cloudiness". It's for xplanetFX, and explained with pictures here (not a long read).

Thanks in advance.

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Re: Clouds

Post by snibgo » 2019-07-13T04:48:48-07:00

The two images were apparently taken at different times. See the night-side lights on the "low-res" image.

The "high-res" image has cloud obscuring the UK and Scandanavia. If you have just that image, how do you know what should be beneath the cloud?
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Re: Clouds

Post by Don B. Cilly » 2019-07-13T07:09:33-07:00

Yeah, well, they are at different times because I got the clouds at different times... crontabs and all...
I thought the difference would be easy to spot anyway.
These are pretty much at the same time (I got them "manually":

Image

Image

The clouds are merged onto the earth: The cloud image I'd like to modify looks like this. (I resized it a lot)

Image

I'd like to make it to this:

Image

Should I try playing with contrast, transparency... any ideas/commands?

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Re: Clouds

Post by snibgo » 2019-07-13T07:47:56-07:00

This is reasonably close:

Code: Select all

magick clexampl.jpg -evaluate Pow 2.2 dkcld1.jpg
Image
If you use ImageMagick v6, use "convert" instead of "magick". Ideally, find a better source image than JPEG-compressed. JPEG is only 8 bits/channel/pixel, and will show banding with fairly heavy processing such as this.
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Re: Clouds

Post by Don B. Cilly » 2019-07-13T09:01:12-07:00

Thanks!
I'll give it a go and will let you know.

I have ImageMagick 6.9.7-4 (on Neon unstable).
JPEG is the image format available at on the serve I get it from, but I only have to convert one image every two hours or so.

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Re: Clouds

Post by Don B. Cilly » 2019-07-13T09:21:22-07:00

Now, that worked pretty much phriqqin' perfect.
You da wizard, mon 8)

It's actually a little bit "grainy", but I can probably smooth that out myself. Good enough really.
It took less that 5 seconds to convert, and It's 5400X2700.

Image

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Re: Clouds

Post by Don B. Cilly » 2019-07-13T09:30:56-07:00

Now, if I can be totally irreverent and pretty obnoxious...
Don't you use xplanetFX? Why not? It's simply beautiful :)

This is a way to get free clouds for it.

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Re: Clouds

Post by snibgo » 2019-07-13T10:17:52-07:00

Good stuff. A small blur, eg "-blur 0x5" for your 5400x2700 images, will smooth the graininess.

If your next stage after ImageMagick doesn't need JPEG, then you could use a 16-bit lossless format such as TIFF.

Raising an image to a power leaves black and white unchanged, darkening or lightening everything between, with some effect on contrast.

Another useful operation is "-sigmoidal-contrast". See http://www.imagemagick.org/script/comma ... l-contrast . This also leaves black and white unchanged, and increases (or decreases) contrast at a central value, doing the opposite at highlights and shadows. It may also affect lightness.
Don wrote:Don't you use xplanetFX? Why not?
Never heard of it. Is http://mein-neues-blog.de/xplanetFX/ the correct link for it? Looks cool, but I don't suppose it works on my Windows machine without X11 or whatever.
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Re: Clouds

Post by Don B. Cilly » 2019-07-13T10:36:59-07:00

Thank you very much.
I'll definitely look into it (like tomorrow or so).

XplanetFX (correct link) does not work on Windows, no.
For that, there' EarthDesk, pretty much the same.

Basically, it's free but you pay for the clouds.
I get my current (low-res) cloud images from them (they work on xplanet).
But, you see, if we can get these free clouds to work well - we pretty much did - you get Earthdesk with the clouds for free :)

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Re: Clouds

Post by Don B. Cilly » 2019-07-15T01:57:26-07:00

We got it almost perfect with -blur 0x1,5.

Thanks again.

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