Cache EXIF details between generations

1 files changed, 9 insertions, 0 deletions

diff --git a/README.md b/README.md
index 52b0bd4..74b17a9 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,8 @@ photoalbum --version
 * `--init` creates `./photoalbum.conf` in the current working directory from the
   default config. It refuses to overwrite an existing file.
 * `--generate` builds the static album.
+* `--force` with `--generate` rebuilds from scratch instead of reusing cached
+  scaled photos, thumbnails, blurs, or EXIF data from the existing output.
 * `--refresh-splash` rewrites only the generated root splash page.
 * `--sync` publishes the generated output directory to configured rsync
   destinations.
@@ -105,6 +107,13 @@ metadata records the generator version and timestamp, config source, template
 directory, supported source image and generated file counts, tarball status, and
 effective settings useful for debugging a published album.
 
+Normal generation preserves reusable generated artifacts from the previous
+`DIST_DIR` while still rerendering HTML, random splash/background choices,
+animation classes, timestamps, and shuffled preview order. Existing scaled
+photos, thumbnails, blurs, and cached EXIF identify output are reused when the
+source image is unchanged. Pass `--force` with `--generate` to skip that cache
+copy and rebuild all generated image artifacts and EXIF data from scratch.
+
 The following long options override config values:
 
 | Option | Config value |