Does the grid cover up the image underneath?

Only where the lines themselves are drawn. If you use a semi-transparent grid color, the image still shows through the lines instead of being fully occluded.

Can I control the line spacing and thickness?

Yes, both the cell size (spacing between lines) and the line thickness in pixels are configurable.

Does the canvas size change?

No, the grid is drawn directly onto the existing canvas at its original size; nothing is cropped or expanded.

What's a good use for this?

Overlaying a reference grid on pixel art, print layouts, or design mockups where evenly-spaced guides help with alignment.

PNG Grid Drawer - Overlay a Grid on an Image

Overview

Introduction

This tool overlays an evenly-spaced grid of lines onto a PNG, computed entirely client-side.

It's useful for adding reference guides, pixel-art grids, or print-layout alignment lines directly onto an image.

What Is PNG Grid Drawer?

A grid-drawing tool that paints horizontal and vertical lines at a fixed pixel interval across the image, alpha-blending the chosen line color onto the existing pixels rather than replacing them outright.

The line spacing, thickness, and color/opacity are all configurable.

How PNG Grid Drawer Works

Starting from the top-left corner, the tool draws a vertical line every `cellSize` pixels and a horizontal line every `cellSize` pixels, each `lineThickness` pixels wide.

Each line pixel is composited over the existing pixel using standard alpha blending, so a semi-transparent line color still lets the underlying image show through.

When To Use PNG Grid Drawer

Use it to add a pixel-art reference grid over a sprite for size and alignment checking.

It's also useful for creating a print-layout guide grid directly baked into a design mockup.

Often used alongside PNG Parts Splitter and PNG Multiplier.

Features

Advantages

Runs entirely client-side; your image never leaves the browser.
Alpha-blended lines let the underlying image show through instead of being fully occluded.
Configurable spacing, thickness, and color for a wide range of grid styles.

Limitations

The grid always starts at the top-left corner (0,0); it can't be offset to align with off-grid content.
Lines are drawn as hard-edged rectangles, not antialiased, matching this site's other pixel-level effect tools.

Examples

Add a pixel-art reference grid

Input

A 64x64 PNG sprite, cell size 8, thickness 1, black at 40% opacity

Output

A 64x64 PNG with a faint 8x8 grid overlaid, the sprite still visible underneath

The semi-transparent black lines mark 8-pixel boundaries without hiding the sprite's own colors.

Add a bold layout guide grid

Input

A 800x600 PNG mockup, cell size 100, thickness 2, red at full opacity

Output

An 800x600 PNG with solid red gridlines every 100 pixels

A fully opaque grid color completely replaces the pixels it covers.

Best Practices & Notes

Best Practices

Use a lower opacity grid color so the underlying image stays legible through the lines.
Choose a cell size that evenly divides your image's dimensions for a clean, complete grid at the edges.

Developer Notes

The pure grid-drawing math lives in a lib function operating on a plain Uint8ClampedArray pixel buffer with no DOM dependency, alpha-blending each line pixel with a small local compositing helper rather than simply overwriting existing pixel values.

PNG Grid Drawer Use Cases

Overlaying a pixel-art reference grid on a sprite
Adding print-layout alignment guides to a mockup
Creating graph-paper-style backgrounds

Common Mistakes

Expecting the grid to start from the image's center — it always starts at the top-left corner.
Using a fully opaque grid color and being surprised the underlying image is hidden along every line.

Tips

Combine with the parts splitter tool to preview exactly where a grid split would land before actually cutting the image.
Use a contrasting grid color for dark images and a darker one for light images to keep the lines visible.

PNG Grid Drawer