Methods and systems for transmitting an image with thumbnail data
摘要
說明書
Exemplary embodiments address these and other issues relating to image transmission and receipt. The techniques described improve the speed and rendering quality of an image (such as a JPEG) and are particularly well-suited to an end-to-end encrypted environment (E2EE).
According to exemplary embodiments, the image may be analyzed on the sending-client side and the image data may be broken into multiple categories or segments. In one embodiment, the image data is broken into two chunks: a thumbnail chunk, and a high-quality image chunk. The full-quality image chunk depends on the thumbnail chunk, such that the image data from the thumbnail chunk is re-used when rendering the full image using the high-quality image chunk.
The sending client determines the chunks, identifies the chunk sizes, and calculates hashed-based message authentication codes (HMACs) over each of the chunks. The image data may be encrypted and uploaded to a blob store, and a notification message may be sent to the receiving client with the determined image information and a suitable decryption key. The receiving client may first download the thumbnail chunk and use it to render a thumbnail; in some embodiments, the thumbnail chunk may be automatically downloaded when a message is received. The user on the receiving side can view the automatically downloaded thumbnail and determine if they wish to download the full image at high quality.
