READING THE SCOPE
Drag to orbit · Scroll/pinch to zoom · Each pixel plotted by hue (angle), saturation (radius), luminance (height).
Sky clusters near center-blue ·
Sodium drifts yellow-orange ·
Airglow = slight green offset
Reference Chip Strip
Z0 BlackZ5 MidZ9 White
STAR ANALYSISDetects point sources, estimates spectral type from color, maps light pollution direction.
Bortle Scale
Detected Stars
Load a photo to detect stars
Light Pollution Direction
NOISE / SNR ANALYSISSignal-to-noise ratio per zone. Low SNR = stacking needed. Hot pixels and banding detected from dark zone variance.
SNR by Zone
Sensor Analysis
Hot Pixel Map
STACKING GUIDESNR <5: Stack 16+ frames · SNR 5–15: Stack 4–8 frames · SNR >15: Single frame usable for bright regions
STAR FWHM — FOCUS QUALITYFull Width Half Maximum measures star sharpness. Lower = sharper. Round stars = good tracking. Elongated = trailing or tilt.
Focus Score
Star FWHM Distribution
Sharpness Map
GRADIENT / VIGNETTE ANALYSISReveals uneven illumination — light pollution gradients, lens falloff, and stray light. Ideal frame is uniform across all cells.
Luminance Gradient Map
Corner Analysis
Gradient Statistics
CHROMATIC ABERRATIONRGB channel misalignment on high-contrast edges. Measured as pixel offset between R and B channels. <0.5px = excellent · >2px = visible CA.
CA Severity Map
Channel Analysis
WHITE BALANCE EYEDROPPERClick any neutral area on your photo to set white balance from that exact pixel. The tool calculates the Kelvin equivalent and applies it as a sky color temperature correction.
Click on a neutral area of your photo to sample white balance
Sampled White Balance
Auto Neutral Detection
SELECTIVE COLOR ISOLATIONClick any pixel on your photo to highlight all similar-hued pixels. Useful for isolating sodium glow, airglow, Milky Way dust, and sky regions separately.
Click on your photo to isolate that color
Hue Tolerance
Tolerance20°
Selected Color Info
No color selected
REGION ANALYZERDrag a box on your photo to analyze that specific area in detail — zone distribution, average K, SNR, and color preservation for the selected region only.
Drag on your photo to select a region
Region Statistics
No region selected
Region Zone Distribution
EXPOSURE CALCULATORMaximum shutter speed before star trailing. Uses the NPF rule (most accurate) and the classic 500 rule.
Camera Settings
Focal Length24mm
Aperture f/f/2.8
ISO3200
Sensor
Results
Star Trail Reference
At the calculated shutter speed, stars at the celestial equator move exactly 0.5× their diameter — the NPF threshold. Stars near Polaris can use 3–4× longer exposures.
SKY QUALITY METER + SITE SCORESQM value estimated from dark-zone pixel luminance. Site score combines Bortle, sky Kelvin, pollution severity and light source type into a composite grade.
SQM Estimate
Site Evaluation Score
Score Breakdown
EXIF DATACamera metadata extracted directly from the image file. Load a JPEG with embedded EXIF to see full shooting data.
Camera & Lens
Exposure Settings
Location & Time
PLATE SOLVINGIdentify what's in your image — sky coordinates, field of view, constellation, nearby objects. Uses your EXIF location/time for instant estimates, or Astrometry.net for a precise plate solution.
Sky from EXIF Location
Load an image with GPS and timestamp EXIF to see sky position.
Desktop app needed for automatic solving.
Running from a local file — browser security prevents direct API calls. Get the SpectraVision Desktop app for one-click plate solving, or use the manual entry below.
Manual Plate Data Entry
Solve at nova.astrometry.net (upload your image there), then paste the result here. SpectraVision will draw the star overlay from your solution. Or enter data from Stellarium, SkySafari, or any plate solver.
RA centre (decimal °)
Dec centre (decimal °)
Field radius (°)
Rotation (° from N)
Pixel scale (arcsec/px, optional)
Finding RA/Dec on nova.astrometry.net: After solving, click your submission → the result page shows RA, Dec, and field size in the Calibration section.
ANALYSIS REPORTFull scientific summary of your image. Export as HTML to share with the Utah Astrophotography community or save for your records.
Step 1 — Select My Color Vision Type
Step 2 — Live Sky Balance
Target:
Targeting: True Dark Night
⬜
Load an image to begin
Kelvin
—
target ~10500K
R ratio
—
target 0.265
B ratio
—
target 0.408
Step 3 — Adjust These Sliders
Move sliders below. The verdict above updates instantly. Stop when you see a green ✓.
Sky Color TempKEY
6500K
Controls the blue-warm balance of your sky. Increase to cool a warm/orange sky. Target: 9000–11000K for true dark night.
Light Pollution Remove
0
Removes warm orange glow from light pollution in dark sky zones. Increase if Kelvin reads below 7000K.
Shadow Lift
0
Lifts detail out of crushed dark zones. Increase if foreground and shadow areas look identical in brightness.
Shadow Color
0
Increases or decreases color in dark zones. Helps when shadows look flat or colorless.
Step 4 — Or Start From a Preset
Tap Your Sky to Sample
Tap the darkest sky area in your photo to measure it
Step 5 — Channel Enhancement
Boost specific color channels and emission wavelengths independently. Kelvin correction alone can't reveal H-alpha nebulae, airglow, or OIII — these controls target those specific signatures.
Boost R, G, or B channels independently. If you have reduced sensitivity to a channel, boost it here so you can see and judge it accurately.
R Channel Gain
0
Reveals red nebulae (H-alpha), warm dust lanes, red stars. Essential for Protanopia.
G Channel Gain
0
Reveals airglow (OI 557.7nm), green nebulae, natural sky green. Essential for Deuteranomaly.
B Channel Gain
0
Reveals night sky blue, OIII blue-green, star colour differences. Essential for Tritanopia.
Target specific astronomical emission wavelengths. These exist outside the Kelvin scale — boosting them reveals structure invisible to simple temperature correction.
H-alpha (656nm)
0
Reveals ionised hydrogen regions — emission nebulae, supernova remnants. Red pixels with low G and B. Invisible to Protanopia without boost.
Airglow OI (557nm)
0
Reveals the characteristic atmospheric green glow. Marks pristine dark sky zones. Invisible to Deuteranomaly without boost.
OIII (501nm)
0
Reveals doubly-ionised oxygen — planetary nebulae, some supernova remnants. A blue-green signature distinct from sky blue.
Dust Contrast
0
Enhances brownish dust lane contrast in Milky Way core. Targets pixels with warm tone and mid-brightness — reveals structure across the galactic plane.
Apply the scientifically optimal enhancement for your specific CVD type. Each preset boosts channels and emission lines in the right direction for your condition.
Step 6 — False Color Assist
Remaps colors you cannot perceive to colors you can — without changing the science. H-alpha red becomes yellow for Protanopes. Airglow green becomes cyan for Deuteranopes. Use for editing only; disable before final export.
Select your CVD type above to see what False Color Assist will remap for your condition.
⚠ False Color is active. This is an editing aid only. Disable before exporting your final image.
ASTROMODIFIED CAMERA BALANCEHa-modified cameras flood the red channel with H-alpha (656nm), making standard Kelvin balance impossible. These tools separate emission signal from sky background and give scientifically meaningful readings for modified sensors.
Step 1 — Camera Modification Type
Select your camera modification type above.
Step 2 — H-alpha Background Suppression
Reduces the broadband red elevation in sky background only. True Ha emission regions are automatically detected and protected.
Ha Suppression
0
Reduces red channel in sky zones only. Emission regions (Ha nebulae) are detected and protected. Start at 40–60 for standard Ha-mod.
OIII Boost
0
Boosts blue-green in OIII-signature pixels. Reveals nebula structure suppressed by the red-heavy balance.
Emission Threshold
12
How much redder (%) a pixel must be above background to be classified as Ha emission rather than sky. Default 12 works for most Ha-mod cameras.
Step 3 — Background Sky Balance
Measures non-emission sky pixels only — gives a scientifically meaningful Kelvin and R:B reading independent of H-alpha contamination.
Target:
⬜
Load an image to begin
Sky K (ex-Ha)
—
target ~10500K
R ratio (ex-Ha)
—
target 0.265
B ratio (ex-Ha)
—
target 0.408
These readings exclude Ha emission pixels. A green verdict means the background sky is scientifically accurate for the chosen target — regardless of how the H-alpha regions look.
Step 4 — H-alpha Signal Mapping
Map the extracted Ha signal to a display colour for presentation or export.
Natural mode: corrects broadband red bias while preserving true H-alpha in the red channel.
Emission Detection Map
Red = Ha emission regions (protected) · Blue = sky background (corrected) · Dark = foreground
Ha emissionSky backgroundForeground
PRINT CALIBRATIONDiagnose why your prints come out dark or with odd colors. Complete each step to build a compensation profile for your monitor and viewing environment.
⚠ Step 0 — Blue Light Filter Check
Critical: Disable blue light filters before calibrating or printing
Night Shift, Night Light, and similar features shift your display warm — removing blue and adding orange. This makes your image look correctly balanced on screen but prints will come out with a heavy orange cast. These filters must be OFF during editing and before printing.
Look at these two patches. The left should be pure vivid blue. The right should be neutral white. If either looks orange or warm, your blue light filter is active.
How to turn off blue light filtering:
iPhone/iPad: Settings → Display & Brightness → Night Shift → turn off. Or Control Center → press and hold brightness slider → Night Shift.
Mac: System Settings → Displays → Night Shift → Schedule: Off.
Windows: Settings → System → Display → Night Light → toggle off.
Cannot turn it off? Select your filter strength below so we can compensate:
✓ Great — display is showing accurate colors. Continue below.
Step 1 — Viewing Environment
What lighting will you view the prints under? This affects recommended white point.
Step 2 — Gamma Test
The checkerboard and solid patch below should look identical in brightness when viewed from arm's length (squint slightly). Select which matches what you see.
Checkerboard
Solid gray (186)
Step 3 — Shadow Detail (Luminance)
How many of these dark patches can you distinguish from pure black? Count from left.
Step 4 — Highlight Detail
How many near-white patches can you distinguish from pure white?
Step 5 — Color Neutrality
These patches are mathematically neutral gray (R=G=B). Do they appear neutral, or do they have a color cast?
Print Calibration Profile
Complete steps 1–5 to generate your profile
RAW file loaded. Click Auto Balance Sky above to apply recommended starting corrections for RAW images (contrast, blacks, sky temp). Then fine-tune with the sliders.
