Google Web Picture Format (.webp)
RFC استانداردWebP is a modern image format developed by Google that provides superior lossless and lossy compression for web images, supporting both alpha transparency and animated frames.
تبدیل JPG به WEBP
مبدل رایگان JPG به WEBP درون مرورگر. فایلها را فورا روی دستگاه خود تبدیل کنید.
فشردهسازی آنلاین WebP
فشردهسازی ۱۰۰٪ خصوصی در مرورگر - فایلها هرگز دستگاه شما را ترک نمیکنند
بررسی و فراداده
سیستمعاملها و تحلیلگرهای فایل، فایلهای WebP را با بررسی توالی بایتهای دودویی ابتدایی شناسایی میکنند:
امضای هدر در سطح بایت (Magic Bytes)
سیستمعاملها و تحلیلگرهای فایل، فایلهای WebP را با بررسی توالی بایتهای دودویی ابتدایی شناسایی میکنند:
امضای HEX (آفست 0):
52 49 46 46نمایش ASCII: RIFF
استانداردسازی: RFC 6386 / RIFF Container Specification
مشخصات فنی
| معماری کانتینر | Resource Interchange File Format (RIFF) container with 'WEBP' FourCC |
| فشردهسازی | Lossy VP8 predictive intra-frame coding & Lossless VP8L spatial entropy coding |
| ترتیب بایتها (Endianness) | Little-Endian for RIFF chunk sizes and container tags |
| فضاهای رنگی | sRGB, Embedded ICC Profiles (via VP8X extended header) |
| کانالها و ساختار | RGB + Alpha (8-bit per channel) |
| حداکثر ابعاد | 16,383 x 16,383 pixels (14-bit unsigned integers) |
| شفافیت مشخصات | Full 8-bit alpha channel transparency in both lossy and lossless modes |
| استریمینگ و پیشرونده | Progressive decoding supported via incremental VP8 block decoding |
ماتریس مقایسه فنی: WebP در برابر رقبا
| ویژگی فنی | WebP (فعلی) | JPEG | PNG | AVIF |
|---|---|---|---|---|
| Supported Compression Modes | Both Lossy (VP8) and Lossless (VP8L) | Lossy only | Lossless only | Both Lossy (AV1) and Lossless |
| Alpha Transparency | Yes (both lossy and lossless) | No | Yes | Yes |
| Animation Support | Yes (multi-frame with frame delays) | No | Requires APNG extension | Yes (AVIF image sequences) |
| HDR / Wide Color Gamut | 8-bit sRGB only | 8-bit standard | 8-bit & 16-bit | 10-bit & 12-bit native HDR |
| Browser Support | 97%+ global support across all modern browsers | 100% universal | 100% universal | 93%+ modern browsers |
حالتهای رایج خرابی و راهنمای بازیابی هگز
⚠️ Browser fails to display WebP image or shows broken image icon.
علت ریشهای: RIFF payload length header (bytes 4-7) does not match the actual byte length on disk.
بازیابی: Recalculate total file size minus 8 bytes, and patch the 4-byte Little-Endian unsigned integer at offset 0x04.
⚠️ Decoder fails with 'Invalid FourCC: Expected WEBP'.
علت ریشهای: Bytes 8-11 do not contain the ASCII characters 'WEBP'.
بازیابی: Verify offset 0x08 contains 0x57 0x45 0x42 0x50 ('WEBP') and that the chunk header matches 'VP8 ' or 'VP8L'.
تحلیل امنیتی و بردارهای حمله تجزیهکننده (Parser)
WebP parsing gained intense security scrutiny following CVE-2023-4863, leading to widespread sandbox hardening across all major web browsers.
بردارهای حمله شناختهشده
- CVE-2023-4863: Heap buffer overflow in libwebp's BuildHuffmanTable function when parsing invalid lossless Huffman tables, allowing remote code execution.
- Integer overflow when decoding oversized animation frame canvas dimensions.
بهترین روشهای پدافندی: Ensure all client and server libraries use libwebp 1.3.2 or later. Decode WebP files in memory-sandboxed worker threads.
تاریخچه و نقاط عطف
مزایا و نقاط قوت کلیدی
- Lossy WebP images are 25%–35% smaller than comparable JPEG images at identical SSIM quality.
- Lossless WebP is typically 26% smaller than standard PNG.
- Single unified format handles photos, graphics with transparency, and lightweight animated clips.
محدودیتها و معایب فنی
- Maximum dimensions capped at 16,383 x 16,383 pixels, preventing ultra-high resolution panoramic imagery.
- Only supports 8-bit color depth (no native 10-bit or 12-bit HDR support).
- Encoding complex lossy images requires more CPU cycles than legacy JPEG encoders.
نکات فنی جالب
- WebP is based on the keyframe intra-prediction algorithms of Google's open-source VP8 video codec.
- The RIFF container used by WebP is the exact same container architecture used by classic Microsoft AVI and WAV files.
- Animated WebP files are typically 60%–80% smaller than animated GIFs.
سوالات فنی متداول
Can WebP completely replace both PNG and JPEG?
Yes. For web use, WebP provides superior compression for both photographic content (replacing JPEG) and transparent graphics (replacing PNG). Its universal browser support makes it a primary format for modern web optimization.
Why is WebP lossless compression more efficient than PNG?
WebP lossless uses advanced spatial predictors, color transform decorrelation, a localized color cache, and entropy-coded 2D transforms, resulting in files that are typically 26% smaller than optimal PNGs.
Does WebP support animation?
Yes. WebP supports multi-frame animation with variable frame delays, full alpha transparency per frame, and disposal methods, delivering 60%–80% smaller payloads than traditional animated GIFs.
جفتهای تبدیل مرتبط با WebP
Convert JPEG photos into modern WebP format to reduce web payload size by 25-35%.
Convert WebP images into universal JPEG format for legacy applications and older device compatibility.
Convert PNG graphics into lossless WebP format to save bandwidth while maintaining full alpha transparency.
Convert WebP images into standard PNG format for editing in graphics software.
Convert Animated WebP image sequences into universally supported animated GIF files.