ip4ap tutorial review, astronomy technology today, july 2015

ASTRONOMYTECHNOLOGY TODAYYour Complete Guide to Astronomical Equipment

Volume 9 • Issue 3July-August 2015 $6.00 US

SKY-WATCHER ESPRIT APOS • IP4AP PIXINSIGHT TUTORIAL SERIESMIRROR VERSUS PRISM STAR DIAGONALS

Explore ScientificAR152 AchromaticRefractorA Quality 6-inch Refractor for Every Budget!

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Astronomy TECHNOLOGY TODAY 9

Contents

In This Issue12 Editor’s Note

Better Late Than NeverBy Gary Parkerson

32 The Explore Scientific AR152 Achromatic RefractorA Quality 6-inch Refactor for Every Budget!By Dr. James R Dire

37 The Sky-Watcher Esprit AposAmong the Best Apo Values on the Market TodayBy Richard Wright

In This Issue45 The IP4AP PixInsight Tutorial Series

Take Your Image-Processing Skills to a New LevelBy Ron Brecher

51 Mirror Versus Prism Star DiagonalsKnowing When to Use WhichBy André Van der Elst

56 Astro Tips, Tricks & Novel SolutionsHooked On – A Low-Tech SolutionBy David Lloyd-Jones

Cover Story: Pages 32-35

Our cover features Explore Scientific’s 152-mm f/6.5 AR152, a fast, affordable,high-quality 6-inch achromatic refractor.Dr. James Dire, no stranger to high-endrefractors, provides his impressions of thebig refractor after using it extensively for both high- and low-magnification visual observations. The backgroundimage is from Ron Brecher’s report in thisissue on IP4AP’s PixInsight tutorials anddemonstrates the dramatic improvementshe was able to obtain from applying thoselessons to maximization of PixInsight’smulti-scale function.

ASTRONOMYTECHNOLOGY TODAYYour Complete Guide to Astronomical Equipment

Volume 9 • Issue 3May-June 2015 $6.00 US

SKY-WATCHER ESPRIT APOS • IP4AP PIXINSIGHT TUTORIAL SERIESMIRROR VERSUS PRISM STAR DIAGONALS

Explore ScientificAR152 AchromaticRefractorA Quality 6-inch Refractor for Every Budget!

The IP4AP PixInsight Tutorial Series

I’m a bit of a PixInsight evangelist; I’lladmit it. So before I get into my review ofthe IP4AP’s PixInsight tutorial series, I amgoing to first explain why I consider Pix-Insight to be the most powerful and com-prehensive software package for deep-skyimage processing.

PixInsight has the ability to handleeverything from pre-processing to linearprocessing (before stretching) and postprocessing (after stretching). It handles virtually every image file format up to 64-bit and has effective tools for just about anything an image processor might

want to do.One of the key advantages of PixIn-

sight compared to Adobe Photoshop, whichis still probably the most widely usedastro-image processing tool, is that PixIn-sight was developed “for astro-imagers, byastro-imagers,” and everything is included


By Ron Brecher

Take Your Image-ProcessingSkills to a New Level

Figure 1: The BatchPreprocessing script handles all of the “data crunching” required to calibrate, correct, align, and combine a set ofone-shot color or mono-filtered data, and produces master frames ready for further processing. This script is outlined in IP4AP PixIn-sight Part- 1, tutorial PI-6_Stack-1.

when you purchase it – there are no plug-ins or toolkits to buy although manythird-party scripts may be downloaded forfree. A single PixInsight license allows anunlimited number of installations on fourdifferent platforms: Windows, OSX,Linux, and BSD. So far, I have paid forPixInsight once, when I purchased it in2009. All of the many updates since havebeen free of charge. Some other packagescharge monthly fees, or require a sub-scription to be renewed annually in orderto receive updates.

PixInsight’s tools include processes,coded in C++, and scripts, coded in JavaScript. This scripting capability makesPixInsight extremely versatile, with morethan 150 processing tools currently avail-able. Anyone can contribute a script, andthe community will collaborate to im-prove the most useful scripts; some evenget converted to processes.

One of the most important scripts isBatchPreprocessing (Figure 1), whichtakes care of calibrating images with darks,biases, and flats, debayering one-shot colorimages, killing hot and cold pixels, regis-tering a group of images, and integratingthem into master frames ready for post-processing.

In addition to processes and scripts,the PixelMath tool (Figure 2) further ex-pands PixInsight’s capabilities. PixelMath

46 Astronomy TECHNOLOGY TODAY

THE IP4AP PIXINSIGHT TUTORIAL SERIES

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Figure 2: PixelMath can be used to blend images before and after a process is applied.In this case, the image was sharpened with UnsharpMask and the before and after im-ages were blended 60:40.

allows pixel-by-pixel mathematicalprocesses to be applied to images. I fre-quently use PixelMath to blend images,for example, before and after applyingsharpening. Many PixelMath expressionsare also freely available for users to down-load, including expressions that replicatePhotoshop’s various Blend Modes. PixIn-sight also has excellent mask-generationtools, and PixelMath can be used to makemore complex masks by selectively com-bining simple masks.

Two important features of PixInsightare Workspaces and Projects. A Workspaceis like a PixInsight desktop. I often use thefollowing Workspaces to keep everythingorganized: (1) Cleanup – for cleaning upchannels with cropping and backgroundmodelization tools, (2) RGB – for pro-cessing the RGB channels alone, (3) Lu-minance – for processing the luminancechannel alone, (4) LRGB – for combiningthe Luminance and RGB images, and (5)Multi-scale – for working on the large andsmall details in an image separately.

Projects (Figure 3) allow you to saveyour Workspaces, images, previews, andicons together in a single file. Once a proj-ect is saved, it can be re-opened later andbring you back to where you left off in thelast session. Not only can you resume yourwork-flow, but you have full access to re-turn to former history states, as well. Thisis similar to Photoshop’s .PSD file, onlymore powerful.

Before I get carried away with thevirtues of PixInsight, I need to point outthat, like any other software package, Pix-Insight can be daunting to learn. Docu-mentation within the program isincomplete, and what’s available can behard for a newbie to understand. Fortu-nately, there are excellent free resources on-line: video tutorials, the PixInsight Forum,and even written tutorials like mine (seehttp://astrodoc.ca/deep-sky-image-pro-cessing-workflow/). These resourcestaught me enough to know I was justbarely scratching the surface of PI’s capa-bilities. It was about that time that I con-

sidered buying the IP4AP.com tutorial se-ries created by Warren Keller with RogelioBernal Andreo, both accomplished as-trophotographers in their own right.

I’m a try-before-you-buy person, andwas pleased that the first six tutorials inIP4AP PixInsight Part 1 (Figure 4) are freeand available at the click of a mouse(http://www.ip4ap.com/pixinsight_part1.

htm). Excluding the introduction to theseries (P1-0), the free tutorials includemore than 30 minutes of informationabout PixInsight. I learned things aboutthe user interface that I hadn’t figured outfor myself in my previous four-plus yearsof using PI. So, I decided to buy the firstseries. After devouring the information init, I purchased the second, and then the



Figure 3: This IP4AP screen shot shows that a PixInsight project contains all of the im-ages, masks, previews, icons, history states, and other settings so that you can easilypick up where you left off. Projects can store multiple Workspaces – another useful fea-ture of PixInsight that makes it easier to organize files. Project files are conceptuallysimilar to Photoshop .PSD files.

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third series. I still regularly consult the tu-torials for fine details about complex top-ics like deconvolution, multi-scaleprocessing, and noise reduction.

Each tutorial in the three-part IP4APPixInsight series is from four to eight min-utes long and focuses on one or two PIprocessing tools. There are a total of morethan 60 tutorials. The information is pro-vided by the narrator in a clear, slow voice,with very good illustrations onscreen, in-cluding call-out boxes, zooming, andother tools for emphasis. One of the thingsI really like is that the tutorials recom-mend specific settings, or ways to deter-mine them, for various PI tools (calledprocesses or scripts, as noted above). Theauthors don’t shy away from advancedtopics like stitching mosaics, blending nar-row-band data, and multi-scale processing.These are covered in consecutive tutorials.

One of the mini-series that really tookmy image processing with PixInsight to anew level was on multi-scale processing(Figure 5). In multi-scale processing, an

48 Astronomy TECHNOLOGY TODAY


Figure 4: The first five chapters of Part 1 of the IP4AP PixInsight Tutorial Series are freeand can be downloaded from http://ip4ap.com/pixinsight_part1.htm. They provide a thor-ough introduction to the user interface.

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image is broken down into several imagesbased on the scale of details. For example,an image containing only small features,like stars, can be extracted from the par-ent image. This small-scale image can thenbe subtracted from the parent image tocreate a large-scale image. The two partscan be processed separately and then re-combined. For example, color saturationand sharpness of stars can be increasedwhile large-scale nebulosity can besmoothed and made more contrasty.

The Parts 1 through 3 of the IP4AP

PixInsight tutorial series are available eitheras an online subscription or on DVD. Inaddition to their 22 to 27 individual tuto-rials, each series part includes images andweb links referenced in the tutorials.Among the things I found especially help-ful were the sets of processing icons thatWarren uses, which can be imported di-rectly into PI and used in your work-flow.Part 2 also includes a sample PI projectthat can be downloaded so you can learnPI even if you don’t have your own data towork with.

Every new user of PI – and probablymost experienced users – will benefit fromthe IP4AP tutorials from www.ip4ap.com.For a very modest cost, they helped mebuild my PI repertoire and improve myimages immensely. In the context of pay-ing thousands of dollars for equipment,computers, and software, IP4AP’s tutorialsprovide outstanding value for the money.I would recommend them to anyone whois serious about harnessing PixInsight’s vastcapabilities to make beautiful space photos(Figure 6).



Figure 5: This screenshot from the third series tutorial designated “PI-14_Multiscale-2”shows how small-scale structures can be extracted from an image. The tutorial goes onto show how large-structures can be isolated, permitting separate processing of largeand small-scale features, which can then be recombined using PixelMath.

Figure 6: The proof is in the pudding! The same data processed by the authorbefore (top) and after (bottom) learninghow to use multi-scale techniques from IP4AP.

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ip4ap tutorial review, astronomy technology today, july 2015

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