In June to August this year, I had the good fortune to capture a full set of broadband and narrowband data for the iconic Helix Nebula. 

After recently posting a colour image (LRGB), I went the next steps to use the Ha and OIII captures to enhance the LRGB image. The process involves extracting the Red, Green and Blue components of the original RGB image. Ha is then used to supplement the Red Channel in proportion to its bandwidth versus the Red Broadband filter bandwidth. A Boost Factor allows the amount of additon to be controlled. The process was repeated for the Blue and Green channels, with the OIII filter data used for the enhancement, in each case with an independent Boost factor. The Boost Factors were varied to give an aesthetically pleasing result. I used the Color Mask Script in PixInsight, to create a mask of the central core areas, which are predominantly blue-green. Without masking, where the Ha and OIII areas overlap, the image becomes white and detail is potentially lost. When the Ha was used to enhance the Red channel, an inverse of the Blue mask was used to prevent it overwhelming the central area, whilst, when the Blue and Green channels were both enhanced with OIII, the Blue Mask was used to prevent the peripheral areas of the OIII having too much impact on the inner areas of Ha. These added dramatically to the colour intensity and detail, and in the case of the Ha, made the outer reaches of the nebula much more apparent. 
Revision H shows the original colour image which can be accessed via the mouse over and allows the enhancement with the narrowband filters to be made clear.

“The Helix Nebula (also known as NGC 7293 or Caldwell 63) is a planetary nebula (PN) located in the constellation Aquarius. Discovered by Karl Ludwig Harding, most likely before 1824, this object is one of the closest of all the bright planetary nebulae to Earth. The distance, measured by the Gaia mission, is 655±13 light-years.The Helix Nebula is an example of a planetary nebula, formed by an intermediate to low-mass star, which sheds its outer layers near the end of its evolution. Gases from the star in the surrounding space appear, from our vantage point, as if we are looking down a helix structure. The remnant central stellar core, known as the central star (CS) of the planetary nebula, is destined to become a white dwarf star. The observed glow of the central star is so energetic that it causes the previously expelled gases to brightly fluoresce.The nebula is in the constellation of Aquarius, and lies about 650 light-years away, spanning about 0.8 parsecs (2.5 light-years). Its age is estimated to be 10600 +2300/−1200 years, based on the ratio of its size to its measured expansion rate of 31 km/s.The Helix Nebula is thought to be shaped like a prolate spheroid with strong density concentrations toward the filled disk along the equatorial plane, whose major axis is inclined about 21° to 37° from our vantage point. The size of the inner disk is 8×19 arcmin in diameter (0.52 pc); the outer torus is 12×22 arcmin in diameter (0.77 pc); and the outer-most ring is about 25 arcmin in diameter (1.76 pc). The outer-most ring appears flattened on one side due to it colliding with the ambient interstellar medium.Expansion of the whole planetary nebula structure is estimated to have occurred in the last 6,560 years, and 12,100 years for the inner disk. Spectroscopically, the outer ring's expansion rate is 40 km/s, and about 32 km/s for the inner disk.” – Wikipedia (abridged)