Image Metadata Viewer

Introduction

An image file name rarely tells you enough. IMG_4829.jpg could be 4032×3024 or a resized thumbnail. Upload validators reject oversize assets silently. Layout bugs trace back to a hero banner that is 2400 wide when CSS expects 1920. Before resizing, compressing, or converting, you need a quick read on file type, byte size, dimensions, and aspect ratio—without opening Photoshop or running identify in a terminal.

Certoflow's Image Metadata Viewer inspects basic properties of any image you select locally. File name, MIME type, file size, width, height, aspect ratio, and last modified timestamp appear in a structured list. Nothing uploads; FileReader loads the file only in browser memory for the duration of your session.

What this tool does

Upload an image and view:

Field	Example
File name	hero-banner.webp
File type	image/webp
File size	Human-readable (KB/MB)
Width	1920px
Height	1080px
Aspect ratio	1.78 (width ÷ height, two decimals)
Last modified	Locale-formatted timestamp from file metadata

Dimensions reflect decoded bitmap size after the browser loads the image—not always identical to embedded EXIF sensor tags when orientation tags affect display elsewhere.

How it works

Certoflow reads the selected File object from the input element, passes it to loadImageFromFile, and reads img.width and img.height after decode completes. File size comes from file.size bytes. MIME type uses file.type when the browser provides it (may be empty for extension-only guesses on some OS paths). Last modified uses file.lastModified converted to local time string.

EXIF depth: This viewer focuses on file and dimension metadata accessible without a full EXIF parser. Camera make/model, GPS, shutter speed, and ISO are not displayed in the current implementation—plan accordingly for photography workflows needing deep EXIF.

No network requests carry your file. Metadata extraction is synchronous aside from image decode I/O in memory.

Real-world examples

Pre-upload CMS check. Editor requires images under 2 MB and at least 1200 px wide. Metadata viewer confirms 1.4 MB and 2400×1600 before upload succeeds first try.

Debugging stretched layout. CSS uses aspect-ratio: 16/9 but image looks wrong. Viewer shows actual ratio 1.33—asset is 4:3, explaining letterboxing not a CSS bug.

Client asset handoff audit. Agency receives logo-final.png. Viewer reports 512×512 and 89 KB—matches contract spec before integrating into production repo.

WebP vs PNG confusion. File extension says .png but MIME reads image/webp after a bad rename. Catch mismatch before pipeline scripts fail.

Screenshot archive triage. Folder of unknown captures—sort by opening each briefly to log dimensions into a spreadsheet for documentation standards enforcement.

Common mistakes

Expecting full EXIF camera data. Basic viewer by design. Use dedicated EXIF tools for lens, exposure, and GPS fields.

Trusting filename extensions alone. Extensions lie after manual renames. MIME type and decode dimensions are authoritative for web work.

Confusing displayed size with intrinsic pixels. Retina @2x assets need width/height here doubled relative to CSS pixels—viewer shows intrinsic bitmap size, not CSS layout size.

Assuming orientation tags appear in width/height. Some JPEGs store landscape pixels with EXIF rotation; browser decode for this tool may report dimensions before you mentally rotate—cross-check visual preview in Rotate Image if orientation seems swapped.

Using last modified as capture date. lastModified reflects filesystem timestamp, not EXIF DateTimeOriginal. Do not use for forensic chronology.

Uploading to untrusted sites for "properties". Certoflow stays local; still avoid metadata checks on confidential scans on shared kiosks.

Use cases

Developers verify assets before committing to git repos or CDN uploads. Designers confirm deliverable specs without Creative Cloud. QA engineers document expected vs actual dimensions in bug reports. Students prove image meets assignment resolution requirements.

SEO specialists validate Open Graph image dimensions against platform docs. IT support inspect attachments when users report "upload failed" tickets without clear errors.

Pair with Image Dimension Checker for a fast orientation label, Image Resizer when metadata shows oversize dimensions, and format converters when MIME type does not match downstream requirements.

FAQ

Is my image uploaded?

No. FileReader loads it only in browser memory.

Does it read EXIF camera data?

Basic file and dimension metadata only. Deep EXIF parsing is not shown in the current tool.

Which formats work?

Any image format the browser can decode—JPEG, PNG, WebP, GIF, etc.

How is aspect ratio calculated?

Width divided by height, displayed to two decimal places (e.g., 1.78 for 16:9).

Why is file type "unknown"?

Some files lack MIME metadata from the OS; extension may still hint format but decode success is the real test.

Do width and height include EXIF orientation?

Dimensions reflect decoded bitmap as reported by the Image object—behavior may vary with orientation tags across browsers.

Can I inspect multiple files quickly?

Select one file at a time; re-select to replace metadata panel content.

How is this different from Image Dimension Checker?

Metadata Viewer shows full file info table. Dimension Checker focuses on a large width × height readout with landscape/portrait/square label.