问题描述
我将允许用户上传使用JPEG压缩的300x300图像.有没有办法确定此类图像的最大文件大小?
I'm going to let users upload images of 300x300 compressed with JPEG. Is there a way to determine what the maximum file size of such an image would be?
我可以想象这可以通过以100质量压缩随机噪声来尝试,但是有理论上的最大值吗?
I can imagine this can be tried by compressing random noise at 100 quality, but is there a theoretical maximum?
假设图像是完全不可压缩的随机噪声,是否可以是每个像素3个字节(24位彩色)和元数据的余量?还是压缩后的图像会比原始图像大?
Say that the image is totally uncompressable random noise, could it be 3 bytes per pixel (24-bits colour) and a margin for the metadata? Or could such an image turn out larger than the original when compressed?
推荐答案
因此,对于300x300
图像上的Q=100
,将导致(300 * 300) px * 8.25 bits/px = 742,500 bits = ~ 93 kB
So, for Q=100
on an 300x300
image, that would result in (300 * 300) px * 8.25 bits/px = 742,500 bits = ~ 93 kB
还有无损的JPEG
编码模式,实际上不使用.但它们将具有典型的RGB 24 bits/pixel
.
There are also lossless JPEG
coding modes, which are practically not used . But they would have the RGB typical 24 bits/pixel
.
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