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Compare Images in Two Directories

Source: R/compare_images.R
compare_image_dirs.Rd

Compare all images in a baseline directory against corresponding images in a current directory. Files are matched by relative path (including subdirectories when recursive = TRUE).

Usage

compare_image_dirs(
  baseline_dir,
  current_dir,
  pattern = "\\.(png|jpe?g|webp|tiff|bmp)$",
  recursive = FALSE,
  diff_dir = NULL,
  parallel = FALSE,
  ...
)

Arguments

baseline_dir

Path to the directory containing baseline images.

current_dir

Path to the directory containing current images to compare against baseline.

pattern

Regular expression pattern to match image files (matched case-insensitively). The default matches the file extensions accepted by odiff: .png, .jpg, .jpeg, .webp, .tiff and .bmp. Note that odiff does not accept the .tif extension; such files matched by a custom pattern are reported with reason = "error".

recursive

Logical; if TRUE, search subdirectories recursively. Default is FALSE.

diff_dir

Directory to save diff images. If NULL, no diff images are created.

parallel

Logical; if TRUE, compare images in parallel. See compare_images_batch() for details.

...

Additional arguments passed to compare_images_batch().

Value

A tibble (if available) or data.frame with class odiffr_batch, with one row per baseline image (in baseline file order), containing all columns from compare_images() (including error) plus a leading pair_id column.

Details

The baseline directory is the source of truth. For each image found in baseline_dir matching pattern:

  • If a corresponding file exists in current_dir (same relative path), the two images are compared.

  • If the file is missing from current_dir, a warning is issued and the file is included in the results as a failed row with match = FALSE, reason = "missing", NA diff statistics and diff_output, img2 set to the expected (nonexistent) path, and an explanatory error message. This ensures that a disappearing screenshot fails the comparison. If every file is missing, all rows are "missing".

An error is raised if baseline_dir contains no images matching pattern.

Files that exist only in current_dir (not in baseline_dir) are not compared, but a message is emitted noting how many such files were found.

See also

compare_images_batch() for comparing explicit pairs, compare_images() for single comparisons.

Examples

if (FALSE) { # \dontrun{
# Compare all images in two directories
results <- compare_image_dirs("baseline/", "current/")

# Only compare PNG files
results <- compare_image_dirs("baseline/", "current/", pattern = "\\.png$")

# Include subdirectories and save diff images
results <- compare_image_dirs(
  "baseline/",
  "current/",
  recursive = TRUE,
  diff_dir = "diffs/"
)

# Check which comparisons failed (including missing files)
results[!results$match, ]
} # }