Writing EXIF metadata to captured images

[Tobyntobyn]

I'm searching for a solution to tag EXIF metadata to images from the firmware on the WiseEye 2 controller. I'm developing within the Himax Seeed Grove Vision V2 SDK and have the HX6538 connected to a Raspberry Pi Module 3 camera that captures and writes the images to SD via fastfs_write_image()

With the microcontroller's limited onboard memory, I have been struggling to reliably find a solution on how to tag EXIF metadata to the captured images.

I'm not searching for anything too complicated, however one requirement is the ability to add custom EXIF tags. One other capability is EXIF allows an embedded thumbnail image(jpg) which would be convenient to send the EXIF metadata, including thumbnail, to the phone, on request.

Avenues I have approached so far (all without success for various reasons):

1: TinyEXIF library (doesn't meet requirements as it doesn't allow for writing)

2: Manually inserting APP1 blocks into the images (it corrupts the structure of the jpg image. There is potential that I've writing/inserting the block incorrectly, but after multiple days of inserting in all ways, shapes and forms, it's been paused)

I understand the APP1 block needs to be structured correctly (Starting with 0xFFE1 marker, containing the length of the block, including the Exif identifier and TIFF header and the metadata is formatted as TIFF IFD entries). Also that the APP1 block needs to inserted correctly into the JPG image, typically straight after the SOI (start of image) block:

[SOI] [APP0] [APP1 (EXIF)] [DQT] [SOF] [DHT] [SOS] [Compressed Image Data] [EOI]

3: Creating a pre-built "libexif" library (runs into memory allocation issues when executing certain required functions)

If you have any advice on what EXIF library I could embed into the SDK that meets the HX6538's limitations, or how to correctly insert the APP1 block, I would love to hear about solutions used to achieve this.

Thanks in advance,
Tobyn

[stevehuang82]

Hi Tobyn,

What EXIF information would you like to be tagged in the captured images ? Or just want to add thumbnails to the EXIF metadata?

Steve

[Tobyntobyn]

Hi Steve,

Thanks for your reply.

Primarily wanting to tag EXIF data to images, we're following the Camtrap Datapackage.
With the Media & Observation fields to be tagged to images.
Thumbnails aren't a necessity, but would be beneficial as a feature to have.

Tobyn