Images to PDF
Why is my HEIC file not recognised? (and how to fix it)
By DeckleUpdated
If HEIC to PDF does not recognise a file ending in .heic, the file usually is not a HEIC still photo inside, even though the name says so. Read the message, work out what the file really is, then use the tool for its real format, such as JPG to PDF for a JPEG. Deckle checks the contents before converting, and your file is never changed.
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Photograph
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Diagram
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Scan
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A static PDF page does not preserve motion
How to fix a HEIC file that is not recognised
- Read the message. Under Could not finish this file, Deckle names the file and the reason, for example that the file does not contain the stated image format, that it holds more than one image, or that the decoder could not read it. A photo that is too large is caught earlier: the Create PDF button stays disabled and names it.
- Open the file in Photos or Preview on a Mac, or in the Photos app on an iPhone. Check that it opens as one still photo.
- If the message says the contents are not HEIC, make a copy of the file ending in
.jpgand add it to JPG to PDF. Deckle checks the contents again, so a wrong guess is simply refused. If it is refused there too, try a copy ending in.pngin PNG to PDF. - If it really is HEIC but still fails, export a fresh copy. On a Mac, open it in Preview, choose File > Export and pick HEIC or JPEG in the Format menu (Convert image file types using Preview on Mac).
- Add the new file to the matching tool and choose Create PDF.
What the message means
| Message or reason | What it means | Fix |
|---|---|---|
| Does not contain the stated image format | The name ends in .heic but the contents are something else |
Find the real format and use its tool |
| HEIC sequences with more than one top-level image are not supported | The file holds several images | Export the single image you want as a photo |
| Above the pixel limit for scaling on this device (on the disabled button) | The photo is over 64 megapixels, or 25 megapixels on iPhone and iPad | Convert on a computer, or use a smaller copy |
| This HEIC image would not decode | The decoder could not read this particular file | Export a fresh copy from a photo app |
Deckle checks each file twice. When you add it, the picker accepts names ending in .heic and .heif. Before the conversion runs, Deckle reads the start of the file to confirm it really is a HEIF container. A file that fails the second check is refused with its name in the message, before any page is made.
Why a file can have the wrong extension
It was renamed. Changing photo.jpg to photo.heic does not convert it; it only changes the label. Deckle reads the contents, so a JPEG with a HEIC name is refused by HEIC to PDF and should go to JPG to PDF.
It was converted on the way. Apple notes that photos sent by AirDrop, Messages or email may be shared as JPEG when the receiving device does not support HEIF, and that photos imported over USB may be converted to JPEG (Using HEIF or HEVC media on Apple devices). Some apps and services keep the old name while changing the format.
It holds several images. HEIF can store an image sequence, such as an animation, or a collection of images in one file. Deckle refuses a HEIC with more than one image rather than silently choosing one, so no page goes missing without you knowing. An ordinary Live Photo still is a single image and is not affected.
It is a very small or unusual HEIC. The decoder refuses some very small HEIC images from Apple encoders. Exporting the photo again, or as JPEG, usually solves it.
When the photo is too large
A large photo is usually not refused. Each page keeps up to 16 megapixels on a computer or Android device, and 4 megapixels on iPhone and iPad; a larger photo is scaled down to fit, and the review lists it before you convert. Only a photo above 64 megapixels on a computer, or 25 megapixels on iPhone and iPad, is refused, before it is decoded, with the file named on the disabled Create PDF button.
Apple notes that on supported models the main camera saves 24-megapixel photos by default, with 48 megapixels available as an option (Change advanced camera settings on iPhone). A 24-megapixel photo converts everywhere, though on iPhone and iPad it keeps about a sixth of its pixels. A 48-megapixel photo is refused on iPhone and iPad: copy it to a computer, where it is scaled to 16 megapixels, or set Settings > Camera > Formats > Photo Mode to 24 MP or 12 MP for new photos.
On Windows, the browser often reports no file type for a .heic file. Deckle identifies the photo from its contents instead, so it is not turned away as an unsupported type.
The first HEIC conversion needs a download
The HEIC decoder is downloaded the first time you convert a HEIC file. If your connection drops at that moment, or a network filter blocks it, the conversion fails. Check your connection and try again; a failed download is retried on the next attempt.
Tips
- Trust the contents, not the name. A file's extension is a label anyone can change.
- Set the camera format if you convert often. In Settings > Camera > Formats, Most Compatible saves new photos as JPEG. Apple describes the setting in the page linked above.
- Avoid renaming to force a tool. Renaming a HEIC to
.jpgdoes not make JPG to PDF accept it; it is refused for the same reason. - Keep the original. Converting, renaming or exporting copies never changes the photo in your library.
Frequently asked questions
Can I just rename a HEIC file to JPG?
No. Renaming changes only the label. Export a real JPEG from Photos or Preview, or convert the HEIC directly with HEIC to PDF.
Why does the file open on my Mac but not in HEIC to PDF?
It may hold several images, be over 64 megapixels, or be a variant the decoder refuses. The message says which. Exporting a fresh copy from Preview usually works.
Does Windows need a HEIF extension for Deckle?
No. Deckle decodes HEIC with its own decoder inside the browser rather than with Windows' HEIF support.
Is anything uploaded when the decoder downloads?
No. The decoder is downloaded to your browser; your photo is read on your device and not sent anywhere.
Related tools
- HEIC to PDF to convert HEIC and HEIF photos
- JPG to PDF for files that turn out to be JPEG
- PNG to PDF for files that turn out to be PNG