FITS Studio is designed for the stacked-16_*.fits files created by the Dwarf 3 after a session or Mega Stack. It does not stack sub-frames. Instead, it takes the linear stacked FITS file the scope already created and gives you a clean processing path: background extraction, channel neutralization, optional linear denoise, stretching, white balance, and PNG export.

1) Load your FITS file or the built-in M42 sample.
2) Go to LINEAR and run Background Extraction.
3) Let Channel Neutralization and Statistics Refresh complete automatically.
4) Optionally apply Gentle Linear Denoise.
5) Switch to STRETCH. Open the HISTOGRAM, set the Stretch Point just left of where the data rises, and raise Stretch D until your target becomes visible.
6) Refine with MTF, Asinh, or GHS.
7) Protect bright stars with Highlights or HP in GHS.
8) Finish with White Balance.
9) Export a full-resolution PNG.

From the opening screen, click LOAD SAMPLE FILE — M42 Orion Nebula. This loads a Dwarf 3 sample FITS file so you can follow the guide without needing your own data first.

Always begin in the LINEAR tab. Linear data contains the real signal, but it is dim and low-contrast by nature. The goal here is to clean the image before you amplify anything with a stretch.

Start with POLY-2. It is the best normal starting point for most Dwarf 3 images, especially under suburban skies. Use TPS-RBF only when the background gradient is unusually complex or comes from multiple directions.

Recommended workflow:
• Click GENERATE SAMPLE GRID
• Review accepted and rejected samples
• Click CALCULATE & PREVIEW
• If the correction looks good, click APPLY CORRECTION

After background correction is applied, FITS Studio automatically runs Channel Neutralization and Statistics Refresh.

Channel Neutralization removes residual per-channel sky bias so red, green, and blue share the same background floor before stretching.

Statistics Refresh then recalculates the histogram-based values the STRETCH tab uses.

Gentle Linear Denoise is optional. Use it when the background is noisy and you want to take the edge off before stretching amplifies that noise. A light setting is usually best.

Suggested starting point:
• 20–30% for moderate noise
• Skip it entirely for very deep, clean stacks

The histogram shows the tonal distribution of the image.

General guide:
• Left side = background and dark signal
• Right side = brighter stars and cores
• The main hump near the left is usually normal sky background

The markers represent active control points, depending on the current mode:
• BP (orange) = black point / background clip
• WP (red) = white point in MTF only
• SP (blue dashed) = stretch point in GHS
• LP (green) and HP (amber) = lower and highlight protection in GHS — only visible when active

MTF
Use when you want a simple, straightforward stretch and quick contrast shaping.

Asinh
Use when star colour matters. Asinh is often the safest first stretch for bright-star fields because it tends to preserve star colour better than a harsher stretch.

GHS
Use when you want the most control over faint detail versus highlights. GHS is excellent when you want to shape the stretch more precisely and protect bright cores and stars.

Recommended sequence for the built-in M42 sample:
1) Clean the image in LINEAR
2) Switch to Asinh
3) Open the HISTOGRAM to watch the data as you work
4) Raise Stretch D gradually
5) Watch the bright core and the stars
6) If stars start to get harsh or pale, use Highlights to tame them
7) Fine-tune the background with BP only if needed
8) Finish with White Balance

Recommended sequence:
1) Start from the cleaned linear image
2) Switch to GHS
3) Place SP near the rise of the data
4) Increase Stretch D gently
5) Use HP to protect the bright core and bright stars
6) Use LP only if you want to preserve deeper shadow structure
7) Use Highlights as a finishing control for bright stars
8) Finish with White Balance

Star colour is usually lost because of aggressive highlight handling, not because of a conservative black point.

Best practices:
• Keep BP conservative at first
• Avoid pushing the stretch too hard too early
• In Asinh, use Highlights to tame bright stars
• In GHS, use HP to protect bright stars and the core
• Finish with White Balance using neutral-looking stars as reference

Use White Balance near the end of the workflow, after the structure and brightness are mostly where you want them.

Practical guide:
• If stars look too orange or yellow, reduce Red slightly or raise Blue
• If stars look too blue, raise Red slightly
• Use neutral-looking stars as your reference

When the image looks right, click EXPORT FULL RES PNG. This saves your current processed result as a full-resolution PNG for sharing, archiving, or finishing in another editor.

The image still looks flat
Increase the stretch more gently before pushing BP too far.

The background is too gray
Raise BP slightly, but do it carefully.

Stars are turning white
Stop increasing the main stretch. Use Highlights or HP instead.

The M42 core looks harsh
Back off the stretch slightly and add highlight protection.

The BP marker sits inside the histogram
That can be normal in a conservative stretch. It often means faint signal is being preserved.

The LDR preview looks different from the final stretch
That is expected. The Linear Detail Recovery preview uses its own temporary display stretch so you can see the linear data. Your real stretch settings are untouched and take over after Apply.