Sky & Telescope - March 2022 - 59

Photoshop's native PSD format. Images larger than 2 gigabytes
must be saved as PSB files, the program's " big " format. Both
file types retain every element of an image - adjustment layers,
smart objects, smart filters, and masks - allowing you to
change your mind and re-edit at any time.
Use the layered master to export other versions that need
to be flattened. That includes high-quality TIFFs for printing
or publication, or lower-quality and down-sized JPGs for use
on social media and for e-mailing. To create the latter, use
Export As dialog under File > Export in the pulldown menu.
Long-time users tend to flatten their master images to save
drive space - a bad habit from the days when hard drives cost
hundreds of dollars for mere megabytes of storage. Terabytes
of archival storage are now cheap; your time is not.
#2: Discover Adjustment Layers
Brightness, contrast, and color adjustments are the most
common edits an astrophoto needs. Never apply those from
the Image > Adjustments menu. These are destructive legacy
functions that originated in Photoshop 1.0 way back in 1990.
Instead, add adjustment layers (Layer > New Adjustment
Layer). This capability was introduced in Photoshop 4 in 1996,
yet some photographers still don't use it. Old habits die hard!
Adjustment layers affect what an underlying image looks like
without altering its pixels, preserving its original content.
Adjustment layers allow you to play with each tweak independently,
to get the picture looking just right, either now or
whenever you open the file in future. Adjustment layers are
ideal for anyone afraid of commitment!
- perhaps next year, or just the next day - when you look at
the image with fresh eyes and wonder, " What was I thinking? "
Non-destructive processing also allows you to inspect a
picture days or months later and see exactly what you did to
create it, so you can repeat your success.
Modern methods for using the program also make it
quicker to use. You can tweak adjustments made previously,
even several steps back, without having to redo your work
from that point on. Non-destructive processing provides you
with the freedom to play and experiment. You aren't forced
to work in a linear progression, always worrying if you got a
particular adjustment right before moving on.
#1: Preserve the Layered Master
To enjoy the stress-free benefits of non-destructive processing,
always save your photos as 16-bit, layered master files in
#3: Apply Smart Filters to Smart Objects
Ditto on smart filters, introduced in 2007 with Photoshop
CS3. By converting an image layer into what Adobe calls a
smart object, the original image is protected inside a " container "
so no filter can alter its pixels, only the layer's appearance
when viewed with the filter. For example, it's common
to reduce noise and sharpen a photo by applying filters.
Before doing so, convert the layer into a smart object, with
Filter > Convert for Smart Filters. Any filter that gets applied
can then be readjusted at any time. There's no longer a worry
about adding too much or too little of a filter.
This also applies to third-party add-ons such as Russell
Croman's excellent StarShrink and GradientXTerminator filters
(https://is.gd/CromanPS), noise-reduction plug-ins including
Topaz DeNoise AI (topazlabs.com), as well as my preferred
choice, ON1 NoNoise AI (https://is.gd/nonoiseai).
#4: Don't Erase, Hide with Masks
Layer masks allow you to restrict an adjustment or a filter to
selected parts of a picture, rather than to the whole thing.
Masks are also useful when blending several images into
a single composite. For example, a photograph of a deep-sky
object might be built up from multiple exposures - short
ones for the brightest areas and long ones for the fainter outer
regions. When blending these different exposures, never erase
sk yand tele scope .o r g * MARCH 2022 59
https://www.is.gd/CromanPS http://www.topazlabs.com https://www.is.gd/nonoiseai http://skyandtelescope.org
Sky & Telescope - March 2022

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