twineconvert

free · in-browser · no upload

DICOM to PNG
Converter

Drop your DICOM file. We'll convert it to PNG right here in your browser, your file never leaves your device.

or drop your file

Select your file here to get started

or drop your file here.

Accepts .dcm, .dicom

nothing uploaded no file size cap no signup

How it works

Three steps. No upload, no signup.

  1. 1

    Drop your file

    Click the dropzone above or drag a DICOM from your desktop. Files of any size, there's no upload, so there's no upload limit.

  2. 2

    Convert in your browser

    The conversion runs entirely in this tab using JavaScript and WebAssembly. Your file never touches our servers, we don't have any.

  3. 3

    Download

    Get your PNG the moment the conversion finishes. Convert another, or close the tab.

Files stay on your device

Your file is never uploaded. The entire conversion runs in your browser using WebAssembly. We can't see what you convert because we have no server to see it.

No file size limit

Server converters cap free users at 1-2 GB and gate larger files behind a paid plan. Since nothing uploads, our limit is whatever your browser can handle.

Free, no signup, no ads on conversions

No account required. No watermark on the output. No queue. Drop a file, get a converted file.

Why convert DICOM → PNG

What this conversion is actually for

DICOM is the universal format for medical scans — every X-ray, CT, MRI, ultrasound, mammogram, and PET image from every hospital PACS. But sharing a DICOM with anyone who isn't a radiologist (a patient, a referring physician without DICOM software, a researcher embedding figures in a paper) almost always means converting it to a regular image first. PNG is the right target: lossless, opens in every browser/email/document tool, preserves the exact grayscale gradient. Critically, this conversion runs entirely in your browser — patient data never crosses the network, satisfying HIPAA in a way that upload-based DICOM viewers fundamentally cannot.

A real example

Your patient downloaded their chest CT from their hospital MyChart portal as a folder of `.dcm` files. They emailed you one (`IM-0001-0042.dcm`) asking what it shows. You drop it in this tool, get a `.png` you can open in any image viewer, drop into a slack message, or insert into your consultation note. No HIPAA paperwork, no "please install OsiriX" friction.

Troubleshooting

"Compressed transfer syntax not supported" error.

Your DICOM uses JPEG-baseline / JPEG-lossless / JPEG 2000 / JPEG-LS / RLE pixel compression — these require additional WASM decoders we haven't shipped yet. The fix: decompress with dcmtk's `dcmdjpeg` first (`dcmdjpeg input.dcm output.dcm` produces an uncompressed Explicit VR Little Endian file). Then re-run this converter on output.dcm.

The image looks completely black or completely white.

DICOM's pixel intensities are often outside the 0-255 range (CT scans cover roughly -1000 to 3000 Hounsfield units; many MRIs are 12-bit / 16-bit). We auto-compute the window/level from the data if the file doesn't specify one, but some scans benefit from a specific preset. If you have access to the DICOM workstation, note the recommended window/level for the modality (lung CT is typically WL/WW = -600/1500) and we'll add a windowing UI in a future update.

I want to convert a multi-frame DICOM (cine loop) — only the first frame appears.

Multi-frame DICOMs (typically ultrasound cines or cardiac MRI series) are not yet supported; we extract only the first frame. For a full cine you'll need a dedicated DICOM viewer with movie-export (OsiriX/Horos: File → Export → QuickTime Movie). If you only need still frames, dcmtk's `dcmj2pnm` can split frames into separate PNGs before you re-run this tool.

Formats involved

About DICOM and PNG

DICOM, Digital Imaging and Communications in Medicine

DICOM is the universal medical imaging format — every X-ray, CT scan, MRI, ultrasound, mammogram, PET scan, and most pathology slides from every modern PACS (Picture Archiving and Communication System) is DICOM. The format wraps a pixel-data payload (the actual image) with a rich metadata header carrying patient identifiers, study/series/instance UIDs, imaging modality, acquisition parameters, window/level presets, and per-vendor private tags. Spec maintained by NEMA (National Electrical Manufacturers Association); first published in 1985 as ACR-NEMA 1.0, became DICOM 3.0 in 1993, still actively versioned today. Wire format: 128-byte preamble + `DICM` magic + tagged-value stream where each tag is a (group, element) pair indexing into the DICOM Data Dictionary.

How to open

Hospital workstations open DICOM natively. For desktop viewing: RadiAnt, OsiriX (macOS), Horos (macOS, free), MicroDicom (Windows, free), Weasis (cross-platform Java). For programmatic access: dcmtk (CLI), pydicom (Python), dcm4che (Java). The free MyChart-equivalent apps from most hospital systems also surface DICOMs from your own scans.

Full DICOM format guide →
PNG, Portable Network Graphics

PNG is a lossless image format, the file size is larger than JPG, but every pixel is preserved exactly. It supports full transparency (alpha channel), which JPG cannot. Created in 1996 specifically as a patent-free replacement for GIF, PNG is the standard for screenshots, logos, icons, UI graphics, and any image that needs sharp text or transparent backgrounds.

How to open

Universal support, every OS, browser, and image editor reads PNG. macOS Preview, Windows Photos, and any web browser open PNGs without any conversion step.

Full PNG format guide →

Related tools

Convert other files to PNG

Convert your DICOM to other formats

FAQ

Common questions

Is this DICOM → PNG converter really free?

Yes. No signup, no watermark, no daily file count limit. Every conversion runs in your browser, your file never touches our servers because there are no servers.

Where does my file go when I convert it?

Nowhere. The conversion runs entirely in your browser using JavaScript and WebAssembly. Your file is never uploaded to our servers. We don't have any servers handling files, there's nothing for us to log, store, or accidentally leak.

What's the maximum file size?

Whatever your browser can hold in memory. Practically, this means a few hundred MB on most computers, significantly larger than the 1-2 GB caps that server-upload converters charge for. Very large files (multi-GB) may require closing other browser tabs first.

Why convert DICOM to PNG?

Medical imaging interchange — sharing scans between hospitals, second opinions, research datasets, patient downloads from EHR portals. Screenshots, logos, UI graphics, and any image needing transparency. The most common reason to convert is compatibility, PNG works in places where DICOM doesn't, or vice versa.

How do I open a DICOM file in the first place?

Hospital workstations open DICOM natively. For desktop viewing: RadiAnt, OsiriX (macOS), Horos (macOS, free), MicroDicom (Windows, free), Weasis (cross-platform Java). For programmatic access: dcmtk (CLI), pydicom (Python), dcm4che (Java). The free MyChart-equivalent apps from most hospital systems also surface DICOMs from your own scans.

Does this work offline?

Once the page is loaded, the conversion itself runs entirely offline. The first time you use a tool, your browser downloads the conversion library (a one-time cache). If you reload while offline, the page won't load, but you can install the site as a Progressive Web App for full offline use.

Can I convert multiple files at once?

Single file at a time for now. Batch conversion is on the roadmap, for now, drop one file, download the result, then convert the next.