In this video tutorial we will learn how to stack
images using the Starstax application. Starstax is a free application for star trail image editing and available for Mac OS X, Windows and Linux. You can download the free software from here.
StarStax has introduced Dark images processing technique in their algorithm to reduce the noise in star trail images. On an average you can use 10 to 15 Dark frames per 100 star trail images.
One important thing to keep in mind while creating dark images, is to keep the resolution of the dark frames exactly the same as that of your star trail jpeg images which you have imported in the Starstax software.
Starstax doesn’t support raw image editing, so if you shoot the trails in raw images make sure you convert your RAW files into jpeg images using any RAW converter software’s or Adobe lightroom software.
If you shoot trails in jpeg then you can directly import those images in Starstax. We recommend to shoot in raw and then do some basic editing in Lightroom software and export the images as Jpeg. Checkout our Lightroom basic editing video of star trails here.
Blending modes are used to determine how two photographs are blended into each other.
Starstax has different blending modes features
as below :
1. Lighten : Retains the lightest pixel while stacking images. This is the widely used blending mode for stacking star trail images. You can select optional Comet mode along with Lighten blending mode to get comet like effect in the final star trail image.
2. Gap Filling : Eliminate’s small gaps in star trails.
While shooting star trails due to some incorrect configuration in settings or while changing the batteries of the camera their is some gap between the star movement in between two images.
If we notice this while processing the image, than we can use the Gap filling blending mode to fill the gap between the stars.
We also have threshold tool for Gap filing. You can access this tool from top right side, below the preference tool. We can configure the threshold and amount from this tool.
3. Comet Mode : Fading trails effect to the end of the star trails simulating the look of comet trails. This is an optional feature and available with lighten and gap filling modes.
4. Darken : Retains the darkest pixel of two images while stacking. This blending mode is not used for star trails, as you will end up getting weird looking star trail image.
5. Add : Adds pixels in the stack. It keeps on adding pixels between two images while stacking the star trail images.
6. Subtract : This blending mode compares the color information in each channel and subtracts the blend color from the base color. The resulting negative values in the images are clipped to zero.
7. Multiply : This blending mode compares the color information in each channel and multiplies the base color by the blend color. The resulting color in the star trail image is always a darker color.
8. Average : Averages the pixels of all the images in the stack. You can use this mode to reduce random noise from the set of star trail images, thereby creating smoother images.
9. Average + Increase Exposure : Averages the pixels in the stack and increase exposure. This mode will give you same result like the above Average blending mode but with enhanced exposure.
10. Average + Decrease Exposure : Averages the pixels in the stack and decrease exposure. This blending mode will give you same result like the Average blending mode but with decreased exposure.
Lighten and Gap filling mode are widely used for star trail image stacking.
StarStax also has an amazing feature of saving cumulative images.
These images are nothing but stacked images saved after each image is processed. We can use these images for creating beautiful star trail time lapse video.
Checkout this star trails in a time lapse video created using the cumulative images.