.heic vs. .heics images

[jsx97]

1. Create a Pages document with two empty pages
2. Export this document as PDF
3. Open this PDF with Preview and export it as HEIC

Note that resulting file is simply .heic, not .heics, despite it contains multiple images. Why is that?

 

[iStorm]

Why would you be expecting it to be .heics? Computers don't know English grammar.

HEIC is just a container format...kinda like a zip file. It could contain one HEIF image, or it could contain many HEIF images. HEIC files can also contain audio.

 

[organicCPU]

Although computers don't know English grammar, the inventors of file extension sometimes do.

I guess that exporting a PDF in preview as HEIC, won´t generate an image sequence in High Efficiency Image File Format (HEIF), but simply a file containing multiple images, a so called image collection.
An image sequence (.heics) would be comparable to an animated gif, while an image collection (.heic) is like an album containing multiple still images. Both types of files contain images that are HEVC-encoded.

From: https://en.wikipedia.org/wiki/High_Efficiency_Image_File_Format

HEIF files containing HEVC-encoded images are also known as HEIC files

From: https://www.loc.gov/preservation/digital/formats/fdd/fdd000525.shtml#sign

.heic is used for HEIF file containing one or more HEVC coded image items. This is the format introduced by Apple in 2017 as an in-camera format for iOS devices. .heics is used for image sequences.

For a quite good technical explanation and examples, have a look at:

HEIF Technical Information - High Efficiency Image File Format

High Efficiency Image File Format (HEIF, ISO/IEC 23008-12) specifies the storage of individual images, image sequences and their metadata into a container file conforming to the ISO Base Media File Format (ISO/IEC 14496-12).

nokiatech.github.io

HEIF Example Images - High Efficiency Image File Format

HEIF example gallery to demonstrate storage of still images, image bursts, animations, derived images, and non-destructive image processing.

nokiatech.github.io