PostgreSQL视频去重 图片去重系列1

PostgreSQL 在视频、图片去重，图像搜索业务中的应用

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图片搜索

PostgreSQL的图像搜索插件使用了非常主流的Haar wavelet技术对图像进行变换后存储

gist 索引方法(支持pattern和signature类型), 以及KNN操作符，可以用于搜索相似度

1,建立图片表

create table image (id serial, data bytea);

2,导入图片到数据库

insert into image(data) select pg_read_binary_file('文件全路径');

错误：

ERROR: absolute path not allowed

PGDATA 为/var/lib/pgsql/9.6/data/，在 vi /usr/lib/systemd/system/postgresql-9.5.service里面有

拷贝文件到该目录后

insert into image(data) select pg_read_binary_file('./2/1K7A9699.JPG');

3, 将图片转换成 patten 和 signature,很耗时

CREATE TABLE pat AS (SELECT id, shuffle_pattern(pattern) AS pattern, pattern2signature(pattern) AS signature FROM ( SELECT id, jpeg2pattern(data) AS pattern FROM image) x );

4,创建索引

ALTER TABLE pat ADD PRIMARY KEY (id);CREATE INDEX pat_signature_idx ON pat USING gist (signature);

5,相似度排行

SELECT id, smlr FROM ( SELECT id, pattern <-> (SELECT pattern FROM pat WHERE id = 74) AS smlr FROM pat WHERE id <> 74 ORDER BY signature <-> (SELECT signature FROM pat WHERE id = 74) LIMIT 100) x ORDER BY x.smlr ASC LIMIT 10;

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视频去重

抽取视频中的关键帧

1,建立图片表

2,导入图片到数据库

3, 将图片转换成 patten 和 signature

CREATE TABLE pat AS ( SELECT id, movie_id, shuffle_pattern(pattern) AS pattern, pattern2signature(pattern) AS signature FROM ( SELECT id, movie_id, jpeg2pattern(data) AS pattern FROM image ) x );

create table targer_table as select * from source_table 是会复制表结构+表数据，

https://stackoverflow.com/questions/4629979/nested-select-statement-in-sql-server

SELECT name FROM (SELECT name FROM agentinformation) 这种是不对的

You need to alias the subquery.

SELECT name FROM (SELECT name FROM agentinformation) a

or to be more explicit

SELECT a.name FROM (SELECT name FROM agentinformation) a

即

select x.id, x.movie_id...

4.

计算不同视频的相似度

select t1.movie_id, t1.id, t1.signature<->t2.signature from

pat t1 join pat t2 on (t1.movie_id<>t2.movie_id)

order by t1.signature<->t2.signature desc

or

select t1.movie_id, t1.id, t1.signature<->t2.signature from

pat t1 join pat t2 on (t1.movie_id<>t2.movie_id)

where t1.signature<->t2.signature > 0.9

order by t1.signature<->t2.signature desc

多上面红色那一行，其它一样

报错：

ERROR: function jpeg2pattern(bytea) does not exist

这个是因为扩展 imgsmlr安装不正确

\dx命令查看所有已安装的扩展模块

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imgsmlr

$ cd imgsmlr$ export PGHOME=/usr/pgsql-9.6$ export PATH=$PGHOME/bin:$PATH:.$ make USE_PGXS=1$ make USE_PGXS=1 install

psql -U postgres -d exampledb -h 127.0.0.1 -p 5432

then exeute the sql.

create extension imgsmlr;

查看下

\dx命令查看所有已安装的扩展模块

然后执行

CREATE TABLE pat AS (SELECT id, shuffle_pattern(pattern) AS pattern, pattern2signature(pattern) AS signature FROM ( SELECT id, jpeg2pattern(data) AS pattern FROM image) x );

记得结束加分号

The idea is to find top N similar images by signature using GiST index. Then find top n (n < N) similar images by pattern from top N similar images by signature.

参考

https://github.com/digoal/blog/blob/master/201611/20161126_01.md

下一步需要测试增量添加图片