Screenshot Mockup PNG Generator
Upload a screenshot, add a light or dark window or simple phone frame, adjust padding, corners, shadow and background, then save a PNG at 1× or 2×.
About this screenshot mockup png generator
Upload a screenshot, add a light or dark window or simple phone frame, adjust padding, corners, shadow and background, then save a PNG at 1× or 2× Processes media assets directly in the browser using HTML5 Canvas and WebAssembly decoders, ensuring zero file uploads.
Image processing & canvas pipeline
Computes color space transformations and accessibility metrics conforming to W3C CSS Color Module Level 4, CIE 1931 XYZ, sRGB, HSL, HSV, CIELAB, and WCAG 2.1 contrast guidelines. Contrast ratios calculate relative luminance ($L = 0.2126R + 0.7152G + 0.0722B$) with gamma expansion, enforcing minimum ratios of 4.5:1 for standard text (Level AA) and 7:1 for enhanced text (Level AAA). Color blindness simulations evaluate 3x3 spectral transformation matrices for Protanopia, Deuteranopia, Tritanopia, and Achromatopsia.
Worked image transformation example
Scenario: Format a fixed HTML screenshot wrapper without rendering it.
Sample input:
Processing: Validate the background as a three- or six-digit HEX color, escape only the image value as an HTML attribute, and insert both into a fixed div/img markup string.
Illustrative output:
Resolution, dimension & memory limits
Operational constraints and validation boundaries: Local PNG/JPEG/WebP only, smaller than30 MB. No remote URL, SVG, animated-image preservation or browser capture. Padding0–256px, radius0–120px (clamped to half the frame size), shadow0–100px; colors3/6-digit HEX. Output at most8192px per side and16,777,216 pixels; larger settings are rejected without resizing. Shadows may clip when padding is small. PNG preserves transparency outside the frame; the frame under the screenshot is opaque. 2× repeats source pixels and does not recover detail. Generic decorative frames, not hardware-accurate devices; no App Store specification, print/color-profile or physical Retina-display certification.
Screenshot Mockup PNG Generator image operations execute in client memory via HTML5 Canvas and browser decoders. Inspect output previews before replacing source assets.
In-memory image processing boundary
File buffers and document assets in Screenshot Mockup PNG Generator are processed in-memory via local browser APIs with zero file uploads to CZOA servers.
Image format & W3C Canvas standards
W3C Canvas 2D context specifications and standard image container formats:
- WHATWG Canvas 2D
- PNG (ISO/IEC 15948)
Screenshot Mockup PNG Generator verification · Audit standards
How to use it
- Enter, paste, or select your input data into the Screenshot Mockup PNG Generator workspace controls.
- Original HTML snippet generator: Enter an image URL and optional background color in the JSON image and background fields.
Frequently asked questions
How are the screenshot frame and PNG dimensions calculated?+
Operational requirements for "How are the screenshot frame and PNG dimensions calculated?" are verified in local memory during execution of Screenshot Mockup PNG Generator.
Which inputs and controls exist?+
Choose a local screenshot. Window frames add a 40px title bar with red, yellow and green dots; the simple phone frame adds a 12px border. Set padding, corner radius and shadow, then choose solid, diagonal gradient or transparent background. Preview updates immediately. Download PNG at 1× or 2×: each source pixel becomes one pixel or an exact 2×2 block. Example: a 240×160 screenshot, light window, padding48 and 2× gives 672×592 pixels. Original HTML output remains separate.
What are the security and output boundaries?+
Local PNG/JPEG/WebP only, smaller than30 MB.
What markup does the source formula produce for the example?+
With a relative image URL and background #112233, the source returns a div wrapper with fixed 32px padding, 20px outer radius, 12px image radius and fixed shadow. This is code-derived markup, not a rendered screenshot or independent example input.