HDR (High Dynamic Range)

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Introduction

HDR is the abbreviation of High Dynamic Range, which is an image technology that aims to present richer and more realistic visual effects by expanding the dynamic range of images.

File Structure

File header: contains image metadata, such as size, color depth, etc.
Data area: stores the actual pixel value of the image, usually in floating point type, representing brightness and color information.
Format and extension: The extension is often “.hdr”, and the format may include Radiance RGBE, etc.

Pros

**High dynamic range: **HDR files can record a wider range of brightness than traditional images, thereby retaining more image details. This allows HDR images to display more realistic and delicate effects, especially when dealing with high-contrast scenes.
**Rich colors and details: **Because HDR files record more brightness information, they can also present richer colors and details. This makes HDR images better in color reproduction and detail expression, providing more possibilities for image processing and post-editing.
**Support for multiple application scenarios: **HDR technology is widely used in photography, filmmaking, game development and other fields. As a carrier of HDR technology, HDR files can meet the needs of different application scenarios and provide a better visual experience for professionals and ordinary users.

Cons

Large file size: Since HDR files record high-precision floating-point pixel values, their file size is usually large. This may lead to certain challenges in storing, transmitting, and processing HDR files, especially in resource-constrained environments.
Compatibility limitations: Although HDR technology has been widely used, not all devices and software support the reading and editing of HDR files. This may cause users to encounter compatibility issues when processing HDR files, requiring additional conversion or processing.
Slow rendering speed: When rendering with HDR files, the rendering speed may be relatively slow because more brightness information and details need to be processed. This may affect user productivity, especially when dealing with large-scale or complex scenes.

Application Scenario

The production of HDR images usually requires synthesis from multiple original images with different exposure levels, such as by taking a series of photos with different exposures and using specific software to synthesize them into an image with a higher dynamic range. HDR technology can also be applied to photography and film production to improve the quality and viewing experience of images by capturing a wider range of brightness and details.

Example

HDR file.

Comparison of SDR and HDR images.