Lightroom to Photoshop file size becomes massive

[K-ozDragon]

I was editing an image in Lightroom, and needed to do some quick clean up. So I used the "import to Photoshop" feature in order to do this. I made one copy of the file, and then a new layer. I used various heal tools on the new layer. Nothing exotic on the healing, just removing dust spots. When done with the healing, I made a consolidated stamp layer (al+ctrl+shift+E). I then closed the document to import back into Lightroom. I sat and waited for the image to upload to the cloud so I could edit it. After 2 hours, it still hadn't uploaded. So I just left my computer on and went home. Several hours later, it finally updated. At home, I tried to finish the editing the image in Lightroom mobile, and then export. After pressing the export button, I again waited over 2 hours for the image to download so it could be exported. I simply gave up after 2.5 hours, and just made the changes in Lightroom.

I am now looking at the file in my Lightroom library, and it is 1.15gb. This is massive. The file is saved as a .tif, and I thought that when Photoshop exported the file, it flattened the image into one singular image. This seems to be true, as pressing "edit in photoshop" on that same file opens it as a single image again in Photoshop with all the changes that were previously made saved, and no layers to edit. So if it isn't saving the layers, why is the image so large?

My file dimensions are 6720x4480 (240ppi). The entire Photoshop image was 4 layers, with one of them being a clear new layer used for healing. Photoshop and Lightroom are the latest versions. If I flatten the image in Photoshop, it drops it down to 175mb. Still large, but far more managaeable. I haven't tried uploading this image, as I don't have 4 hours to wait on the file to upload. This seems like a massive bug, as saving just a few of these images would rapidly take up all of my storage. Not to mention that several hours to upload and download 1.15gb from the cloud is a bit crazy. I used my work computer and wifi to upload, and then my phone on my home wifi to download. Both internet services are running at normal wifi speeds.

[Kevin Stohlmeyer]

Hi @K-ozDragon are any of your layers smart objects?

[Earth Oliver]

no, that's how adding several layers to an image has always worked... for decades. If you don't want massive files, then don't duplicate the layers several times. 
And are you working in 16 bit?

[K-ozDragon]

Correct, I understand that within Photoshop, the file size gets bigger the more layers you add because each additional layer is data. However, I'm referring to the file size once the image is closed and then put back into Lightroom. Lightroom does not get those additional layers. They are not stored within the file. If I open the photo again from Lightroom and import into Photoshop, there is just a single image. No layers, no saved data, just a single image. I have done this before with images that had way more data in them, and had up to 13 layers, and the file size once imported back to Lightroom was around 300mb at the most. This was just a copy layer, a very tiny heal layer (done on a clear background), and then a stamp layer - yet it was 1.5gb.

Essentially, shouldn't the image be flattened once it is imported back into Lightroom? If I flatten the image within Photoshop, it becomes 175mb. This is reasonable, as the compression changes from raw to .tif. The file is apparrently flattened automatically when imported back into Lightroom, as all of the layers and extra data are gone. So why would the file be 5 times the original size?

[K-ozDragon]

I do have smart layers on two of the images. However, should this matter when the image is imported back into Lightroom? I understand that it would make the file much larger within Photoshop, as I am altering the data and adding more to it. That makes perfect sense. However, when the image is automatically imported back into Lightroom, all of the layer data is lost, as the image is flattened into one final image, and then brought back into Lightroom.

As an example, if I flatten the image within Photoshop, I get a file size of 175mb. When imported back into Lightroom, this stays the same and I get exactly the same image as I do if I don't flatten the image and let Photoshop import back into Lightroom. So why the difference in file size?

Also, if I had edited in 16 bit, that would only double the data to 350mb. It wouldn't make it over 8x larger.

[Earth Oliver]

Sorry, but everything you believe about how this works is totally wrong. Hopefully someone with more patience will be able to help you from here.

[K-ozDragon]

If it's that basic, it should be easy to explain. I'll just have to wait for someone more intelligent to answer, and hopefully less rude.

[D Fosse]

LIghtroom does not support layers. It cannot read layers.

A layered Photoshop file has to be saved with "maximize compatibility" on to be visible in Lightroom. This inserts a flattened composite into the file, and this flattened composite is what Lightroom uses.

For this reason, roundtripping via Photoshop back to Lightroom is very risky and a recipe for confusion - unless you fully understand the implications of this.

[K-ozDragon]

Thank you. I am aware that Lightroom does not read layers, which is why this makes no sense to me. It seems like the image would be automatically flattened upon export from Photoshop when it is automatically imported back into Lightroom. Especially since this is the automatic feature of editing in Photoshop from Lightroom, shouldn't this occur automatically? The fact that it doesn't is why I believe this to be a bug. The image size is being massively inflated, despite the fact that what is being exported is technically a flattened image for Lightroom editing.

[D Fosse]

You still misunderstand. The image is not imported "back into Lightroom". Photoshop just saves out to a location on disk like it always does. It saves with layers and everything else.

The reason it reappears in Lightroom is that a background script is running, which tracks the location and imports the saved file into the Lightroom catalog.

A LIghtroom import is not a physical import of the file. It's just a record of where the file is. Similarly, any Lightroom adjustments are not physical adjustments to the file. They are just text instructions in the Lightroom catalog. If you Export from Lightroom, those instructions are applied and baked into a flat exported file.

In short, Photoshop and Lightroom operate on different basic principles. As a one-way workflow from Lightroom to Photoshop this is invisible and seamless. The problems start when you try to reverse that basic flow. It can be done, but you do need to understand what's happening and take the necessary precautions.

[K-ozDragon]

Ok that makes more sense, thank you for explaining how it works. Since the workflow is supposed to be streamlined, wouldn't it make more sense for Photoshop to take note that the file is being imported automatically from Lightroom, and will be imported back in as a flat file? Therefore it would make sense to automatically do this in order to streamline the workflow?

As it exists now, I have to flatten the final image in order to stamp all of the layers into one image, thereby erasing all of the layers. Or I have to turn on a setting which seems like it should be turned on by default within Photoshop when importing from Lightroom. As part of a steamline experience, having to setup the program to interact specifically with another program made by the exact same company doesn't make a whole lot of sense to me.