You can bring artwork from Photoshop (PSD) files into Illustrator using the Open command, the Place command, the Paste command, and the drag-and-drop feature.
Illustrator supports most Photoshop data, including layer comps, layers, editable text, and paths. This means that you can transfer files between Photoshop and Illustrator without losing the ability to edit the artwork. For easy transfer of files between the two applications, adjustment layers that have visibility turned off are imported (though inaccessible) into Illustrator and restored when exported back to Photoshop.
Spot colors (up to 31 spot channels per file) import as a single N‑Channel raster image, which is placed over the process color image. The spot colors are added to the swatches panel as custom colors with the same name as in Photoshop. Imported spot colors separate correctly.
Duotone PSD files import as flat raster images with a 256‑indexed colorspace and an N‑Channel colorspace containing all of the duotone inks. Because Illustrator uses an N‑Channel, blending mode interactions set in Photoshop may appear differently in Illustrator. Ink colors from old color libraries are set to gray.
In cases where Illustrator must convert the Photoshop data, a warning message appears. For example, when importing a 16‑bit Photoshop file, Illustrator warns you that the image will be imported as an 8‑bit, flat composite.