Apple Photos app export as 16-bit TIFF?

[camner]

I see that it is possible to export images from the Apple Photos app as 16-bit TIFF files. But my understanding is that photos taken with Apple devices (iPhones/iPads) are not taken/stored with 16-bit color depth. So what is the point of having the option to export as 16-bit TIFF files?

As a second question, what is the use of exporting even as 8-bit TIFF files vs JPEG files? Is it only to avoid the compression loss that accompanies saving in jpeg, even as maximum quality?

And finally, does exporting in PNG format avoid the problem of compression loss while resulting in smaller files than exports as TIFF?

 

[Badradio]

16-bit Tiff export is to support people wanting to use Photos to store images from other devices, such as DSLRs. I do that, as I don't do enough photography to justify the cost of something like Lightroom, and I actually like Photos for what it is.

Yes, JPEG is compressed even at 100% quality. Some people just want zero compression, even at the cost of file size, whether it's for print, or to archive their images (without storing a RAW or DNG file).

PNG is still compressed - it just has more options than Jpeg, such as transparency (in higher bit-depth versions).

 

[camner]

@Badradio Thanks for your reply! What you say about the purpose of the capacity to export as a 16-bit tiff makes sense.

So, if the original photo was taken by an iPhone/iPad, then the best quality I can expect to export would be as a jpeg with minimal compression (maximum quality) at original size. Yes?

 

[Badradio]

So, if the original photo was taken by an iPhone/iPad, then the best quality I can expect to export would be as a jpeg with minimal compression (maximum quality) at original size. Yes?

Not exactly. Every time you do an export with compression, the image quality deteriorates - even if only a little. Over multiple exports, it's going to show. When you take the photo, the sensor grabs all of the image data it can, then the device compresses that data to store it. iPhones/iPads currently use the new HVEC codec by default, and the compression is very efficient, so good file size reduction with minimum loss of data. So that image on your device is already compressed a tiny bit. If you export as Jpeg, it's compressed again, even at 100% quality.

For those two compressions, I'd be ok with the quality of the final image. Even in print, you'd have to look super hard to spot anything. If you're really bothered about the final quality of the image, Tiff is a good option, but get ready for that file size to increase significantly. Hope that helps

 

[camner]

OK, thanks. Let me try again to see if I’ve gotten it better than in my first go at it...

Photos taken by an iPhone or iPad are stored as HEIC files, which uses lossy compression but results in a higher quality (and smaller) file than JPEG files. When HEIC files are exported from Photos in JPEG format, a second lossy compression occurs, resulting in some further degradation.

So far so good?

So, if I want to preserve every little bit of quality possible, I should export in TIFF. But, I probably won’t notice the difference between exporting as TIFF and exporting as a minimally compressed JPEG.

Yes?

Now, there will be one further compression that will take place. After exporting from Photos, I’ll import into Lightroom, edit there, and then export final processed photos, as JPEGs.

One additional question....Quality loss from compression is only one factor. Bit depth is another factor. If I understand correctly, iPhones capture 10-bit images. Exporting as JPEG or “standard” TIFF will reduce this to 8-bit, but exporting as 16-bit will allow the color gradations and dynamic range of the 10-bit originals to be preserved. So is the question I should be thinking about whether the additional storage requirements of 16-bit TIFFs is worth the (small?) incremental improvement in image quality?

 

[HDFan]

So, if I want to preserve every little bit of quality possible, I should export in TIFF. But, I probably won’t notice the difference between exporting as TIFF and exporting as a minimally compressed JPEG.

Yes. You can't get anything that isn't in the original HEIC or JPEG.

You can think of exporting as filling a bathtub from a bucket. If you export a compressed file to a higher resolution format, pouring the jpeg bucket into a tiff bathtub, you should preserve the image quality of the jpeg. You don't get any data that isn't in the jpeg. If the bathtub is smaller than the bucket, a lower resolution format, then you are going to lose data.

Right now photos are stored as HEIC or JPG so some of the data from the sensor was already discarded before it was stored. The soon to be released IOS update evidently includes support for RAW files. This will give you the best quality from the iPhones camera. Then an export to TIFF would make sense.

 

[ItWasNotMe]

If you are truly worried about every last little bit of quality then you should also worry about the colourspace of the export. For example if you start with an image that is Adobe RGB and export as sRGB then you potentially change some of the colours.

See https://photographylife.com/srgb-vs-adobe-rgb-vs-prophoto-rgb for an explanation

 

[Badradio]

Also, as you're using Lightroom, it might be worth considering setting your iPhone to store images as Jpegs and importing them directly into Lightroom via a cable rather than exporting. I think HEIC (got the right letters that time...) has similar quality to Jpeg but at reduced file size, so you won't lose quality. And if you want to go ALL IN on quality, you can get a camera app like Halide that lets you shoot in RAW, then import those into Lightroom.