Ask HN: What are best ways to down res JPG images?

1 points by hexeater 6 years ago | 5 comments

Our cloud service has a ton of jpgs loaded by users. The images are loaded, then viewed occasionally by auditors and sometimes automated OCR. So written once and read/viewed ~4 times. We want to look at ways to save storage footprint, and I'd like to down sample the JPGs yet keep enough quality to keep users and automated OCR systems happy.

I'm hoping that someone has studied this problem and any pointers would be greatly appreciated.

uberman 6 years ago |

For text, 8-bit indexed png or if your scans are high quality then black and white indexed png files will be hard to top.

After the downsample, run them through pngquant or advpng. The latter supports zopfli via insane mode and will likely take the longest to compress with the smallest result.

hexeater 6 years ago | |

Thanks for suggestions. Seems like it is a standard process to convert to grey scale prior to OCR anyway. :-)

egdod 6 years ago |

Storage is cheap, just buy another couple of hard drives.

benologist 6 years ago |

Why not just charge for additional storage?

hexeater 6 years ago | |

We don’t charge for storage, it’s just a cost for us.