Write values to DateTimeOriginal tag in image metadata

This function assigns values to the DateTimeOriginal tag in image's EXIF metadata using Exiftool. It can be used when the original DateTimeOriginal values in the metadata were lost for whatever reason. In order to first read the Date/Time values from the data fields in the images, see the function OCRdataFields. After running OCRdataFields and checking its output you can run writeDateTimeOriginal.

writeDateTimeOriginal(DateTimeOriginal, fileNames, parallel, overwrite = FALSE)

Arguments

DateTimeOriginal

character. DateTimeOriginal values to write into EXIF:DateTimeOriginal tag of the files in fileNames.

fileNames

character. Full file names (including directories) of images to process.

parallel

A parallel cluster object. Specify if you wish to run this function in parallel. Provide a cluster object (output of makeCluster()) - optional.

overwrite

logical. Overwrite existing files (TRUE) or create new files while saving the original data as jpg_original files as a backup (FALSE)?

Value

Invisible NULL. The actual output is the JPG images which now have a DateTimeOriginal tag.

Details

The first value in DateTimeOriginal will be assigned to the first image in fileNames, and so on. Both DateTimeOriginal and fileNames can be obtained from the output of OCRdataFields. DateTimeOriginal uses the standard "YYYY-MM-SS HH:MM:SS"" notation. If the values extracted via OCRdataFields are in a different format you'll need to reformat them first. Please provide them as character. Also, before using this function, make sure that the date/time values read by OCRdataFields are correct (sometimes OCR misreads values, so check carefully).

Parallel processing is advised since the function is rather slow (due to calling Exiftool separately on every, so about 1 second per image). If you know how to batch-assign DateTimeOriginal values in one Exiftool call, please let me know.

The function only works on JPG images, not video files.

See also

OCRdataFields

Author

Juergen Niedballa

Examples

if (FALSE) {
# dontrun is to avoid forcing users to install additional dependencies

wd_images_OCR <- system.file("pictures/full_size_for_ocr", package = "camtrapR")

library(magick)

# define geometries
geometry1 <- geometry_area(x_off = 0, y_off = 0, width = 183, height = 37)
geometry2 <- geometry_area(x_off = 196, y_off = 0, width = 200, height = 17)
geometry3 <- geometry_area(x_off = 447, y_off = 0, width = 63, height = 17)
geometry4 <- geometry_area(x_off = 984, y_off = 0, width = 47, height = 17)
geometry5 <- geometry_area(x_off = 0, y_off = 793, width = 320, height = 17)

# combine geometries into list
geometries <- list(date = geometry1, 
                   time = geometry2, 
                   sequence_id = geometry3,
                   temperature = geometry4,
                   camera_model = geometry5)

df_image_data  <- OCRdataFields(inDir = wd_images_OCR,
                                geometries = geometries, 
                                invert = TRUE)       
df_image_data



library(parallel)
library(lubridate)

# prepare DateTimeOriginal column (ymd_hms() automatically respects the PM indicator)
df_image_data$DateTimeOriginal <- paste(df_image_data$date, df_image_data$time)
df_image_data$DateTimeOriginal <- as.character(ymd_hms(df_image_data$DateTimeOriginal))

# create cluster (3 cores)
cl <- makeCluster(3)

# assign new DateTimeOriginal
writeDateTimeOriginal(DateTimeOriginal = df_image_data$DateTimeOriginal,
                      fileNames = df_image_data$filename_full,
                      parallel = cl)
                      
stopCluster(cl)
                   
}