https://github.com/bashrc2/staramp

Amplify stars within night photos
https://github.com/bashrc2/staramp

astrophotography photography

Last synced: 9 days ago
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Amplify stars within night photos

• Host: GitHub
• URL: https://github.com/bashrc2/staramp
• Owner: bashrc2
• License: agpl-3.0
• Created: 2023-09-06T17:44:03.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2023-09-19T10:40:02.000Z (over 1 year ago)
• Last Synced: 2024-11-06T03:47:34.328Z (about 2 months ago)
• Topics: astrophotography, photography
• Language: C
• Homepage:
• Size: 8.61 MB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
**staramp** detects stars within a night photo and then amplifies only the star pixels by some defined percentage, without altering the background.



## Installation

On a Debian based distro:

``` bash

sudo apt install build-essential

```

Then build and install:

``` bash

git clone https://gitlab.com/bashrc2/staramp

cd staramp

make

sudo make install

```

## Usage

An example of use can be seen within the **test.sh** script.

``` bash

staramp --dog 8 --dogthresh 145 --dogamp 80 --miny 0 --maxy 2100 -f images/stars1.png

```

It produces a file called **result.png**

**--dog** specifies the radius for the *difference of gaussians* filter. It should be approximately the same as the width of the stars in pixels within your image.

**--dogthresh** applies a threshold to the *difference of gaussians* filter, so that faint pixels which might just be noise can be excluded.

**--dogamp** the amplification percentage.

**--miny** sets the minimum Y axis coordinate to begin processing at. This is typically 0 (the top of the photo).

**--maxy** sets the maximum Y axis coordinate to end processing at. This can be 0 which means process the whole image, or it can be some other value to exclude any scenery at the bottom of the photo.

**-f** defines the night image to be processed. This must be in PNG format.

You can also exclude areas of the image within specified bounding boxes, by using the **--exclude** option:

``` bash

staramp --dog 12 --dogthresh 140 --dogamp 70 --miny 0 --maxy 0 --exclude "0,1590,1287,2013" -f images/stars2.png

```

Here the bounding box to be excluded has top left coordinate **0,1590** and bottom right coordinate **1287,2013**. If you specify additional numbers then you can have multiple exclusion areas. An example might be:

``` bash

--exclude "(0,1590,1287,2013),(50,100,300,500)"

```

If excluding bounding boxes is insufficient, because the shape of the scenery is not very linear then you can define a polygon inside which the stars should be amplified. The polygon can have up to 127 vertices and is a series of **x,y** coordinates. For example:

``` bash

staramp --dog 12 --dogthresh 140 --dogamp 70 --miny 0 --maxy 0 --inside "(0,0),(3045,0),(3045,2019),(1278,2019),(936,1587),(0,1572)" -f images/stars2.png

```