jpeg压缩比 [英] jpeg compression ratio
问题描述
是否有一个表格给出了在给定质量下jpeg图像的压缩率？
像在维基页面上显示的表格，除了更多的值。
奖金：维基页面上的 [压缩率] 值对所有图片都是真的吗？该比率取决于图像是什么和图像的大小？
这些问题的目的：我试图确定压缩的大小的上限
注意：我不想自己创建表格。我正在寻找其他数据与我自己检查。
我有同样的问题，我很失望，创建这样的表（研究基于单个经典的Lena图像或JPEG墓碑看起来可笑）。这就是为什么我自己学习。我不能说这是完美的，但它绝对比别人更好。
我从不同尺寸的不同设备拍摄了60张现实生活中的照片。我创建了一个脚本，它使用不同的JPEG质量值（它使用我们公司的成像库，但它是基于libjpeg，因此它应该也适用于其他软件）以及将结果保存到CSV文件。经过一些Excel魔术，我来到以下值（注意，我没有计算任何JPEG质量低于55，因为它们似乎对我没有用）：
Q = 55 43.27
Q = 60 36.90
Q = 65 34.24
Q = 70 31.50
Q = 75 26.00
Q = 80 25.06
Q = 85 19.08
Q = 90 14.30
Q = 95 9.88
Q = 100 5.27
说实话，值的离差是显着的（例如对于Q = 55min压缩比是22.91，而最大值是116.55），并且分布不正常。因此，不容易理解什么值应该被视为典型的特定JPEG质量。但我认为这些值是好的作为粗略估计。
我写了一篇博文，解释了我如何收到这些号码。
http://www.graphicsmill.com/blog/2014/11/06/Compression-ratio-for-different-JPEG-quality-values
希望任何人都会觉得有用。
Is there a table that gives the compression ratio of a jpeg image at a given quality?
Something like the table given on the wiki page, except for more values.
A formula could also do the trick.
Bonus: Are the [compression ratio] values on the wiki page roughly true for all images? Does the ratio depend on what the image is and the size of the image?
Purpose of these questions: I am trying to determine the upper bound of the size of a compressed image for a given quality.
Note: I am not looking to make a table myself(I already have). I am looking for other data to check with my own.
I had exactly the same question and I was disappointed that no one created such table (studies based on a single classic Lena image or JPEG tombstone are looking ridiculous). That's why I made my own study. I cannot say that it is perfect, but it is definitely better than others.
I took 60 real life photos from different devices with different dimensions. I created a script which compress them with different JPEG quality values (it uses our company imaging library, but it is based on libjpeg, so it should be fine for other software as well) and saved results to CSV file. After some Excel magic, I came to the following values (note, I did not calculated anything for JPEG quality lower than 55 as they seem to be useless to me):
Q=55 43.27
Q=60 36.90
Q=65 34.24
Q=70 31.50
Q=75 26.00
Q=80 25.06
Q=85 19.08
Q=90 14.30
Q=95 9.88
Q=100 5.27
To tell the truth, the dispersion of the values is significant (e.g. for Q=55 min compression ratio is 22.91 while max value is 116.55) and the distribution is not normal. So it is not so easy to understand what value should be taken as typical for a specific JPEG quality. But I think these values are good as a rough estimate.
I wrote a blog post which explains how I received these numbers.
http://www.graphicsmill.com/blog/2014/11/06/Compression-ratio-for-different-JPEG-quality-values
Hopefully anyone will find it useful.
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