Free online LDT to JPG converter

What the LDT format is

LDT is commonly the extension for the EULUMDAT photometric format used in architectural and technical lighting. It is usually an ASCII data file containing luminaire identification, dimensions, lamp information, luminous flux, mounting details, and measured light-intensity values at different angles.

Lighting manufacturers distribute LDT files for luminaires, while photometric tools and measurement systems create them. You may encounter them when importing a luminaire into DIALux evo, ReluxDesktop, or another lighting-calculation application. An LDT file does not normally contain a photograph, 3D model, or complete rendered room scene.

What the JPG format is

JPG, also called JPEG, is a compressed raster-image format supported by browsers, office applications, image editors, and messaging systems. It is suitable for sharing rendered views, polar diagrams, false-colour illuminance maps, and other visual output from lighting software.

JPG files are smaller than many lossless image formats because they use lossy compression. They are convenient for web pages and presentations, but they can blur small labels, fine grid lines, and numerical annotations.

How to actually convert LDT to JPG

Using lighting software

1. Install a photometric application that supports EULUMDAT, such as DIALux evo or ReluxDesktop.
2. Open the luminaire-selection or import function and load the .ldt file.
3. Choose the required output: a 3D luminaire view, a polar candela diagram, an isolux diagram, or a false-colour lighting result. For a room calculation, place the luminaire in a project and run the calculation first.
4. Use the application's image or report export command, typically under File → Export, Output, or a similar menu, and select JPG/JPEG if available.
5. Set the output resolution and JPEG quality. Use a higher resolution when the image contains measurement labels or technical legends, then save the result as luminaire.jpg.

Menu names differ between versions. If the program exports only PDF or PNG, export to PNG for sharper technical diagrams and convert that image to JPG in an image editor such as GIMP or ImageMagick.

Using the online converter on 101convert.com

You can upload the LDT file to the free converter on 101convert.com, select JPG as the target format, and download the result without installing software. Because LDT is photometric data rather than a standard image, verify that the generated JPG shows the required diagram or visualization; a data conversion cannot reproduce a room render that was not present in the source file.

Quality and compatibility limitations

Converting an LDT file to JPG changes structured photometric measurements into a flat image. The JPG cannot be imported later as an editable luminaire, and it cannot be used for illuminance, glare, energy, or compliance calculations.

The visual result depends on the application and view selected during export. An LDT containing only intensity data may produce a photometric chart, while a realistic room image requires a separately created project, geometry, materials, camera position, and lighting calculation.

Use PNG or PDF instead of JPG when exact labels, thin lines, or numerical values must remain readable. If JPG is required, export at least the final display size—preferably larger—and avoid repeatedly opening and resaving the file, which applies additional lossy compression.