[SOLVED] Plot image from BLOB/RAW

Plot image from BLOB/RAW

I'm trying to use the ROracle package to pull images from a database. The images are stored in the database as BLOBs.

I've managed to get the images into R in "raw" format. Is there a way to convert it from raw into jpeg/png?

This is what I have so far:

con <- dbConnect(drv, username = user,
                 password = pw, dbname=connect.string)

query.string <- paste("select db.img",
                      "from database db",
                      "where db.id = '01234567')")

## run a SQL statement by first creating a resultSet object
rs <- dbSendQuery(con, query.string)
## fetch records from the resultSet into a data.frame
data <- fetch(rs)
## extract all rows
str(data)

> str(data)
'data.frame':   1 obs. of  1 variable:
 $ DATA:List of 1
  ..$ : raw  ff d8 ff e1 ...

Ideally, I could then do something like this:

pic <- rawToJpeg(unlist(data)[1])

which would then allow me to plot/save the image

Solution

Consider using writeBin to transfer the binary data to file:

rawToJpeg <- function(pic_data) {
    f = file(paste0('output.jpeg'), "wb")           # OPEN FILE CONNECTION
    writeBin(pic_data, con = f, useBytes=TRUE)      # TRANSFER RAW DATA
    close(f)                                        # CLOSE FILE CONNECTION
}

rawToJpeg(unlist(data)[1])