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Digital noise comes in several varieties. We call the natural fluctuation of incoming light 'photon shot noise.' The electronics of your camera also introduce uncertainties in the measurement of incident [...]

The genesis for this column comes from my experience with image processing. When I began digital photography in the early 1990s, most amateurs would take pictures totaling a few minutes [...]

CLOSE ENCOUNTER Conjunctions of Jupiter and Saturn - known as "great conjunctions" - occur about every 20 years. Adam Block/ Telescope Live gl SEND YOUR IMAGES TO: Astronomy Reader Gallery, P.O. Box 1612, Waukesha, WI 53187. Please include the date and location of the image and complete photo data: telescope, camera, filters, and exposures. [Extracted from the article]

2. SUPERNOVA IN M82 On the evening of January 21, 2014, an undergraduate class led by astronomer Steve Fossey at the University of London discovered Supernova 2014J in the Cigar [...]

In this column, I want to highlight a few basic ideas concerning image layers and conditional blending modes. Although I'll use Photoshop as the demonstration software, the ideas are applicable [...]

=== Unlike most astronomical targets, comets move quickly. This apparent speed can make both the acquisition and processing of the data challenging. In this column, I'll describe how to create [...]

Q: To avoid dew, do professional observatories heat the mirrors and lenses like we amateurs do? --Luciano Puperi Muller, Guapore, Rio Grande do Sul, Brazil A: As with amateur scopes, [...]

This galactic triplet resides in Virgo. NGC 5560, NGC 5566, and NGC 5569 travel through space together, their gravitational interactions distorting the spiral arms of all three objects. (24-inch RC [...]

STAR CLOUD M24 in Sagittarius shows how 'cloudy' our Milky Way is--not with clouds of water droplets, but, instead, with dust and gas clouds. (3-inch Tele Vue 76 apochromatic refractor [...]

CCD imagers have different challenges than visual observers. Even under light-polluted skies, a small telescope with virtually any digital-imaging device will reveal details not attainable in the visual realm. [??] [...]

The late afternoon sun makes the silhouettes of the telescopes on Kitt Peak difficult to see against the bright blue western sky. Guests anticipate an exciting night as part of [...]

Globular cluster M15 in Pegasus is an object that certainly deserves a common name, but it doesn't have one. This wonder is visible without optics to sharp-eyed observers at a [...]

NGC 6118 lies 83 million light-years away in Serpens. Astronomers classify it as a 'grand design' spiral--one with large well-defined arms. (32-inch Schulman Telescope by RC Optical Systems, SBIG STX-16803 [...]

One of the questions that invariably arises when I speak at the SkyCenter or at other events is whether the astrophotography I present is 'real.' Typically this query deals with [...]

4. CRIMSON DYNAMO Emission nebula Sharpless 2-88 glows with the characteristic red hue of stellar nurseries. Hydrogen in the cloud absorbs radiation from nearby stars and re-emits it as light [...]

Image processing is, at its heart, an exercise in solving problems. Data just don't want to go together and fit nicely like pieces of a jigsaw puzzle. Instead, you must [...]

In this column, I'll explain an easy way to quickly increase contrast in both brightness and color for objects that lack distinct features. Several of the features in Photoshop enhance [...]

N6C 488 is a beautiful, delicately wound spiral galaxy some 90 million light-years away in the constellation Pisces the Fish. The blue regions along the spiral arms are newly formed [...]

Astrophotography is a complex subject with facets that are tedious and technical as well as subtle and sublime. In this article, I would like to steer clear of the technical [...]

What's the first thing you do with CCD images you collect? Most likely, calibrating the images using biases, darks, and flats. But then what? It may not even seem like [...]

This image of spiral galaxy NGC 4414 shows the first color high-resolution depiction of the star stream halo surrounding the galaxy. This feature may be evidence for dwarf galaxies falling [...]

In 1954, Charles Wyckoff had a problem. He needed to freeze atomic bomb explosions on film. The initial flash of light, however, would fog the exposure, which prevented the recording [...]

Representing images in ways other than pixels allows for powerful processing. This subject, based on signal processing, requires a mathematical fluency to understand the concepts fully. Many software programs include [...]

Last month, I presented frightening examples of scattered light --literal ghost images! This time we look at another scary picture and conquer our fear by completely fixing the issue. Image [...]

The feeble photons we collect with telescopes and then record with cameras are easily overwhelmed by other photons that find their way into our exclusive astrophotographic party. For the best [...]

BLACK AND BLUE Although reflection nebula NGC 2185 (the large blue region left of center) appears robust, it took 24 hours of exposures through a 32-inch telescope to create this image. POLAR STAR TRAILS A 16mm lens aimed through Delicate Arch at Arches National Park in Utah captured ninety-eight 30-second exposures to produce this stunning portrait. Please include the date and location of the image and complete photo data: telescope, camera, filters, and exposures. [Extracted from the article]

Field of view (FoV) indicators are fundamental tools for imagers. They can show you whether an object will fit in the FoV created by the combination of the optical system [...]

People often ask how I choose processing techniques. Beyond the rigorous steps of calibration, what remains are artistic choices that blend style and editing. Asking which technique to use next, [...]

Faint to medium-bright stars in an image can be a distraction, making it difficult to appreciate a nebula or galaxy. Using a minimum or erosion filter is a wonderful way [...]

During workshops I deliver at the Mount Lemmon SkyCenter, few processing techniques elicit verbal 'Wows!' from participants. No matter how important standard deviation sigma rejection techniques may be, they just [...]

I have now covered enough material in past articles that we can combine several simple techniques to powerfully process data. In this column, we will take what we learned about [...]

When you begin to apply masks to reveal and hide parts of a layer, you'll realize the economy of global image processing. That's because few processes are equally good on [...]

Spiral galaxy M99 appeared nebulous to 19th-century observers who gave it the moniker 'Pinwheel Nebula.' It lies in the constellation Coma Berenices and glows brightly for a galaxy at magnitude [...]

When I talk about an unfamiliar processing construct such as a mask, I ask people to consider the simplest element of an image--a pixel. A pixel has two attributes: color [...]

No other processing step is so fraught with pitfalls as the decision of how bright to make a luminance image before adding color. One thing is certain: If you impulsively [...]

In my previous column, I explained a method that generally produces vivid LRGB images in a consistent way. And even before I finished writing that tutorial, I could already hear [...]

Last column, I discussed the 'Lighten' and 'Darken' blending modes in Photoshop, which you can use as an effect on an underlying layer. However, there are more powerful methods of [...]