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1. Pass (Print Pass)

Definition:
"Pass" refers to the number of times the print head passes over the same area during printing. Each pass adds another layer of ink, improving image quality and coverage.

Technical Details:

1 Pass: Fastest printing, but image quality is rough with visible banding.

4 Pass: Moderate speed with acceptable quality for large prints.

6 Pass: Balanced quality and speed, good for indoor prints.

8 Pass: High quality with smooth gradation and fine details.

12 Pass: Highest quality, suitable for fine art and detailed graphics but slowest.

Trade-offs:

Increasing Pass improves print quality but slows printing speed and increases ink consumption.

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2. P-Liters (Ink Efficiency - Square Meters per Liter)

Definition:
P-Liters (or "㎡/L") represents how many square meters can be printed with one liter of ink. It is an important metric for estimating ink consumption and cost.

Relationship with Pass:

Higher Pass number means more ink deposited, so P-Liters decreases.

Example estimates:

4 Pass: ~80–100 ㎡/L

8 Pass: ~35–50 ㎡/L

12 Pass: ~20–30 ㎡/L

Factors Influencing P-Liters:

Ink coverage percentage in design.

White ink and varnish use.

Material absorption.

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3. Firing Frequency (Ink Drop Ejection Frequency)

Definition:
The frequency at which the printhead's piezoelectric elements eject ink drops, measured in kHz (thousands of firings per second).

Details:

Higher frequency allows faster printing but requires precise control of ink viscosity and printhead temperature.

Typical frequencies: 5 kHz to 60 kHz depending on printhead model.

Considerations:

Too high frequency can cause printhead clogging or ink splattering.

Optimal frequency balances speed and print quality.

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4. Curves (Color and Ink Limiting Curves)

Definition:
Curves control how color values and ink volumes are mapped from digital files to printer output, optimizing color accuracy and ink usage.

Types:

Linearization Curve: Adjusts printer response for consistent output.

Ink Limiting Curve: Caps maximum ink coverage to prevent smudging.

ICC Profiles: Color management profiles ensuring color consistency between screen and print.

Workflow:
Print test charts → Measure colors → Generate curves → Apply in RIP software.

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5. RIP (Raster Image Processor)

Definition:
Software that converts image files (vector or raster) into printer-ready data, controlling how each dot is printed.

Functions:

Rasterizing images.

Managing color separations (CMYK, White, Varnish).

Setting Pass number, gray levels, feathering, and ink limits.

Handling print queues and job management.

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6. Print Resolution (DPI)

Definition:
Dots Per Inch (DPI) measures print detail sharpness - how many ink dots per inch are printed.

Common Settings:

720 × 600 dpi: Moderate quality, faster print.

1440 × 720 dpi: Higher quality, balanced speed.

1440 × 1440 dpi or higher: Very high quality, slower speed.

Best Practice:
Match DPI to Pass for optimal quality; e.g., 4 Pass with 720 dpi, 8 Pass with 1440 dpi.

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7. Feathering

Definition:
A technique to soften edges by gradually decreasing ink density, eliminating harsh banding and visible seams between passes.

How it works:
Ink droplets overlap in a controlled gradient, smoothing transitions.

Settings:

Feathering percentages can range from 0% (none) to 100% (maximum smoothing).

Higher Pass prints generally use higher feathering for better smoothness.

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8. Grayscale (Variable Dot Size)

Definition:
Using different sized ink droplets to create shades between colors and improve detail and smoothness.

Benefits:

More subtle gradations and color depth.

Reduced ink usage by adjusting droplet sizes based on print area.

Typical Usage:

Low Pass: Binary dots (single size).

Medium Pass: 2–3 gray levels.

High Pass: Multiple gray levels for fine detail (e.g., 7pl, 14pl, 21pl droplets).

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Summary Table

Term	Meaning	Impact
Pass	Number of printhead passes	Print quality, speed, ink usage
P-Liters	Square meters printed per liter	Ink cost, efficiency
Firing Frequency	Ink drop ejection frequency (kHz)	Print speed, stability
Curves	Color and ink volume control	Color accuracy, ink limiting
RIP	Software converting images to dots	Controls print parameters
Print Resolution	DPI, detail level	Image sharpness, speed
Feathering	Softening edge transitions	Eliminates banding
Grayscale	Variable ink droplet sizes	Color depth, gradation smoothness