I tried with both kinds of images, png and targa (had to look for a software that produces targa files - which brought back to good old pov-ray, now at version 3.7, so thanks! )
A png file updates instantly.
A targa file does not. I have background rendering turned off and quitting and restarting FCP X is enough to update the targa image.
So it does appear to be related to the image format.
Interestingly, *some* changes in a targa file trigger FCP X to display the new version.
I added an alpha channel and that caused the new image to display in FCP X. Same with removing the alpha channel, but with other changes it seems that FCP X does not "realize" that the image has in fact changed.
Another interesting twist: FCP X does notice if the image disappears, dutifully displaying the red "missing image" badge. But if then the image is recreated and is different, it may display the old version again... my guess is it cached somewhere by FCP X and once it is back online FCP X does not correctly assess that it has changed.
I wasn't aware that you could not add another layer to an existing PS file when working with FCP. I will send feedback to suggest that. I guess the work around for that would be to add additional layers to a PS file even if they are not used prior to importing into FCP.
I did another test just altering the existing layers color and they updated.
I also ran a test with a layered tiff file, and that file imports as a flattened image, no layers at all! Unless I'm doing something wrong.
So... you want FCP X to do something that Premiere CC and Photoshop CC cannot do even though they're both from Adobe?
A few months ago I heard about exactly the same issues in Premiere CC. Adding a new layer in a PSD file that was used in Premiere caused the file to go offline, and relinking the file to the modified PSD did not reflect the changes made to it. Sounds familiar, doesn't it?
I'm going to spare you the very long thread, but this was the reported issue (May 2014):
Basically if you only change something within a layer in PS, PPro is fine. If you merge or add layers, or do anything like that, it looses the link and doesn't reconnect.
Finally an Adobe rep replied:
Reimport the Adjusted PSD and rebuild the Sequence is all I can say to fix the current issue. In future, add new layers, import them individually and replace or add them to the sequence you started with.
Adobe Video Solutions Consultant ANZ
You can apply exactly the same workarounds with FCP X.
I cannot check if this issue in Pr has been resolved since May, but I haven't heard of any fixes. So you really cannot blame FCP X for not doing something with PSD files that even Adobe cannot do.
As Ronny said: you can't blame Apple for something Adobe is doing wrong.
Try this one (old one since video editing or VFX exist, even before layers existed in PS). Add a new layer in PS. Use the pencil tool to put a 1 pixel dot into the upper left edge and the lower right edge of this layer.
Regarding Layered TiFFs: these are thought to be recognised by other applications as flat while keeping the all PSD file informations intact. This is a perfect idea and can only be done with PS.
If a image file (or layer) is empty it doesn't have any dimensions since there is nothing in there.
This has been around forever.
To make an image (or layer) an image you need at least one pixel. So for example you can have a 1920x1080 a in a PSD file and the file will crop the source. Once you have nothing it will crop it to "null", once you have 1 pixel it will crop it to 1 pixel. And so on.