User Guide

This guide covers everything you need to use GrainLab effectively — from loading your first image to exporting a finished batch.

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1. Loading an Image

You can import images in several ways:

• Drag and drop — drag one or more image files anywhere onto the canvas area.
• Keyboard shortcut — press Ctrl + O (macOS: ⌘ + O) to open the system file picker.
• Film strip ＋ button — click the plus icon at the bottom of the screen to add more images to the gallery.

Supported formats: JPG · PNG · GIF · WebP · BMP · TIFF

If your gallery is empty when the app loads, a built-in example image is loaded automatically so you can start experimenting right away.

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2. Applying a Film Preset

Open the Presets tab in the left panel. Eleven carefully crafted film simulations are available:

Preset	Character
Kodak Portra 400	Classic portrait film — warm tones, soft highlights, flattering skin
Kodak Gold 200	Rich, warm, highly saturated — great for travel
Kodak Ektar 100	Ultra-vivid colors, ultra-fine grain
Kodak Tri-X 400	High-contrast black & white, coarse grain
Fuji Superia 400	Fresh greens, balanced color, excellent skin tones
Fuji C200	Cool and subdued, low contrast — Japanese film aesthetic
Fuji Velvia 50	Extreme saturation, deep blues and greens
Fuji Eterna 500	Cinematic, low saturation, soft shadow detail
Ilford HP5 Plus	Classic black & white with strong grain texture
CineStill 800T	Cool tungsten cast, distinctive red halation glow
Agfa Vista 200	Warm vintage feel, magenta shadows

Hover over a preset card to read its description. Click to apply it instantly to the current image.

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3. Adjusting Effects

Switch to the Adjustments tab to fine-tune each of the 8 independent effect layers.

Use the Simple / Advanced toggle at the top of the panel:

• Simple mode — shows primary sliders for each effect.
• Advanced mode — additionally reveals per-channel Color Toning Wheels (shadows, midtones, highlights) for fine-grained color control.

Effect Reference

Color Grading

Controls the overall tonality of the image.

Parameter	Range	Description
Exposure	−100 → +100	Overall brightness
Temperature	−100 → +100	Cool (blue) ↔ Warm (yellow)
Tint	−100 → +100	Green ↔ Magenta
Saturation	−100 → +100	Color intensity
Contrast	−100 → +100	Tonal separation
Highlights	−100 → +100	Brightest areas
Shadows	−100 → +100	Darkest areas

In Advanced mode, three RGB color pickers let you tint shadows, midtones, and highlights independently (each channel −50 → +50).

Film Grain

Parameter	Range	Description
Intensity	0 → 100	How much grain is visible
Size	1 → 3	Grain particle size
Color Variance	0 → 100	Per-channel color noise (more = color grain)
Shadow Boost	0 → 100	Extra grain in shadow areas
Highlight Reduction	0 → 100	Suppresses grain in bright areas

Vignette

Parameter	Range	Description
Intensity	0 → 100	How dark/light the edges become
Radius	0.5 → 2.0	Size of the clear center area
Feather	0 → 100	How gradually the vignette fades
Color	0 → 100	0 = black vignette, 100 = white vignette

Light Leak

Parameter	Options	Description
Intensity	0 → 100	Strength of the leak
Color	Warm / Cool / Vintage	Tint of the light leak
Position	Top-Left / Top-Right / Bottom-Left / Bottom-Right	Corner where the leak originates

Fade

Parameter	Range	Description
Intensity	0 → 100	Lifts blacks to create a washed, vintage look

Halation

Parameter	Options	Description
Intensity	0 → 100	Glow strength in bright areas
Color	Red / Warm / Gold	Hue of the halation glow
Radius	1 → 20	Spread of the glow

Bloom

Parameter	Range	Description
Intensity	0 → 100	Bloom strength
Threshold	0 → 100	Luminance level above which bloom is applied
Radius	1 → 20	Bloom spread

Tone Curve

A simplified 3-point spline that adjusts luminosity independently in three tonal zones.

Parameter	Range	Description
Shadows	−50 → +50	Lifts or crushes the dark end
Midtones	−50 → +50	Brightens or darkens the mid-gray range
Highlights	−50 → +50	Opens or clips bright areas

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4. Before / After Comparison

Click the compare button in the toolbar (or the icon next to the zoom controls) to enter split-view mode. A draggable divider lets you reveal as much of the original or processed image as you like. Click again to exit.

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5. Exporting a Single Image

1. Click Export in the toolbar, or press Ctrl + S (⌘ + S).
2. Choose the output format:
   • JPEG — use the quality slider (1–100%). Lower values = smaller file.
   • PNG — lossless, larger file.
3. Click Download. The file is saved as {original_name}_film.jpg or {original_name}_film.png.

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6. Batch Processing

1. Open the Batch panel from the toolbar.
2. Select the images from your gallery that you want to process.
3. Choose a preset and an export format.
4. Click Export All.

A film_batch.zip file is generated in your browser and downloaded, containing all processed images. Processing uses a Web Worker so the UI remains responsive during export.

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7. Gallery & Session Persistence

The Film Strip at the bottom of the screen shows thumbnails of all loaded images (72×52 px, center-cropped).

• Click any thumbnail to make that image active.
• Click ＋ to add more images.
• Click the ✕ on a thumbnail to remove that image from the gallery.

All images and their per-image parameter settings are automatically persisted to your browser's IndexedDB database (grainlab_gallery). They are restored the next time you open the app. Clearing your browser's site data will remove the gallery.

Current filter parameters are also saved to localStorage (grainlab_params) so your adjustments survive a page refresh.

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8. Keyboard Shortcuts

Shortcut	Action
Ctrl + O	Open / import image(s)
Ctrl + S	Export current image
Ctrl + +	Zoom in
Ctrl + -	Zoom out
Ctrl + 0	Reset zoom to fit

On macOS, substitute ⌘ for Ctrl.

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9. Language Selection

GrainLab automatically detects your browser's language on first load. You can override it manually using the language selector in the top-right corner. Your choice is persisted to localStorage (lang).

Supported locales: en · zh-CN · zh-TW · ja · ko · fr · de · es · pt