jpeg压缩 - 有损或无损 [英] jpeg compression - lossy or lossless
问题描述
我对JPEG压缩有几个问题。
I have few questions on JPEG Compression.
在我的Windows系统中，我有一些图像处理应用程序。例如，Windows msPaint：它提供一个选项将BMP图像转换为JPEG格式。
In my windows system, I have some image processing application. For example, Windows msPaint: which provides an option to convert BMP image to JPEG format.
任何人都可以告诉我，什么是JPEG压缩这里使用mspaint-是
Can anybody please tell me, what is the JPEG compression here using in mspaint- is it lossy or lossless.
如果有人指的是JPEG标准压缩，它在内部使用的压缩有损或无损？
If somebody is referring to "JPEG Standard compression", which compression it is internally using: lossy or lossless?
提前感谢。
Alvin
Thanks in advance. Alvin
推荐答案
JPEG压缩被认为是有损压缩，因为不可能从
JPEG compression is considered a lossy compression, because it is not possible to build the exact binary from an original source through uncompression.
即使是最高的质量，JPEG也是通过丢弃数据来工作的。你控制质量，以折衷你认为是可接受的损失，仍然有一个公平的代表你的形象。虽然数据丢失了，但是可以看到仍然与未经训练的眼睛相同 - 这就是要点。与用于音频的minidisc相同。
Even at the highest quality, JPEG works by discarding data. You control the quality to trade off what you think is an acceptable loss to still have a fair representation of your image. Although data is lost, what can be seen might still be identical to the untrained eye - and that is the point. The same as what minidisc used to do for audio.
JPEG的目的是使摄像图像在文件大小上更小，用于互联网传输，你可以决定多小，但是如果你想要绝对的质量，像TIFF这样的格式更适合。
The intent for JPEG is to make photographic images smaller in file size for internet transmission, you get to decide how small, but if you want absolute quality a format like TIFF is better suited.
偶尔，TIFF提供无损压缩，但文件大小仍然巨大！
Incidently, TIFF offers a lossless compression, but the file sizes are still massive!
还有一件事...如果你拿一个300 x 500位图并将其转换为JPEG，然后将其转换回来。文件大小仍然相同，因为位图通过存储每个像素的公共位数来工作。但是文件的内容会有很大的不同。在这方面，它可能被天真地视为无损，但在实践中它远不是。
One more thing... If you take a 300 x 500 bitmap and convert it to JPEG, then convert it back. The file size will still be the same, because bitmap works by storing a common number of bits per pixel. But the contents of the file will be quite different. In this regard it might be naively viewed as lossless, but in practical terms it is far from it.
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