What is CPT?

Corel PHOTO-PAINT (CPT) is the native project format for Corel PHOTO-PAINT, preserving layers, masks, and editing history.

What is HDR?

Radiance HDR is an image format that stores high dynamic range pixel data, commonly used for HDRI environment maps and lighting.

When Should You Use CPT vs HDR?

CPT vs HDR: Key Differences

• •CPT uses lossless compression while HDR uses lossless compression — both take the same approach to file size management.
• •Since both CPT and HDR use lossless compression, the quality characteristics are comparable — differences in file size come down to how efficiently each format implements compression.
• •Alpha channel support: HDR lacks transparency support.
• •CPT files are typically Large due to layer data while HDR files range 5-30MB for typical HDR maps
• •CPT is optimized for corel image editing, photo manipulation while HDR is designed for hdri lighting, panoramic photography — choose based on your specific workflow needs

Advantages of CPT

• ✓CPT applies lossless compression specifically calibrated for Corel image editing, photo manipulation.
• ✓CPT enjoys broad native support across operating systems, browsers, and creative tools alike.
• ✓CPT guarantees every bit of the original data survives — no approximations, no shortcuts.
• ✓You will find CPT support built into virtually every tool that handles Corel image editing, photo manipulation — no plugins or converters needed.

Advantages of HDR

• ✓At its core, HDR relies on lossless encoding — a design choice that makes it perfect for HDRI lighting, panoramic photography.
• ✓You won't run into compatibility issues with HDR — it's a universal standard across platforms.
• ✓File size management with HDR: larger files guaranteed to match the original exactly.
• ✓Every major application in the HDRI lighting, panoramic photography space supports HDR natively.

Common Use Cases for CPT to HDR Conversion

• Websites and online content
• Print materials and publications
• Social media posts and ads
• Digital photography and editing
• Graphic design projects
• E-commerce product images

Industry Applications

Best Practices for CPT to HDR Conversion

• →Before converting CPT to HDR, decide whether you need maximum quality or smallest file size — this determines which format truly fits
• →Save a master copy in a lossless format before converting to HDR — you cannot recover detail lost during lossy compression
• →Check the color profile: CPT images may use a wider gamut than HDR supports, causing a visible shift after conversion
• →Resize images to the final display dimensions before converting — this avoids unnecessary processing of oversized files
• →Run a single test conversion first to verify quality meets your standards
• →Strip unnecessary metadata to reduce file size after conversion

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Troubleshooting CPT to HDR Conversion

• !Converting CPT to HDR gives blurry output → increase the quality setting before conversion
• !Colors look different in HDR than CPT → check color profile mismatch (sRGB vs Adobe RGB)
• !File size changed more than expected → HDR uses different compression, file size differences of 2-5x are normal
• !Transparent areas in CPT turned white in HDR → HDR may not support transparency

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