Wading through the variety of image types I receive as a retoucher, the following give me the largest range for creative possibilities and ensure the highest quality for a final image.

#1. EIP Files

What exactly is it? Capture One’s EIP, or advanced image package file, is a format that packages a camera raw image file with all raw adjustments made in Capture One. This can include things such as exposure adjustments, ICC profiles, perspective correction, and many other settings.
Why is it so great? Working with an EIP file in Capture One allows me to work directly with a camera raw file while referencing any processing adjustments made by the photographer or creative team.
When is it not so great? Although considered by many to be the industry standard for capture software, not everyone uses Capture One! So this workflow may not work with every photographer and creative team.

#2 . Camera Raw

What exactly is it? A camera raw file (such as .cr2, nef, .arw, raf) is an unprocessed image containing uncompressed data that, through the use of imaging software, is used to produce a displayable image format (such as .jpeg or .tiff file).
Why is it so great? Working with a camera raw file is akin to a digital negative. Like an .EIP, this file gives me the most flexibility in working with the raw data of the image. It provides the greatest latitude in manipulating things such as exposure values and color rendition while creating the lowest instances of image quality degradation.
When is it not so great? In a project with a span of images that need a consistent look, having a mix of some raw and some processed files can be a detriment. Having to ‘decode’ or assess how some images may have been processed before I receive them creates a challenge in recreating those process steps for their RAW image counterparts.

#3. High Resolution .tiff (AdobeRGB or Profoto Colorspace)

What exactly is it? A full resolution .tiff is a ‘processed’ image with adjustments made in a capture or editing software baked into the file.
Why is it so great? Expertly processed files from a photographer or creative team remove some initial processing time and expedite the retouching decision making. Working with full resolution images allows the greatest flexibility in formatting an image for different media types. It’s much easier to retain image quality by scaling an image down than it is to res it up. The AdobeRGB color space provides a greater spectrum of colors than sRGB, allowing me to more easily prepare the file for print or web (even if the image may end up in sRGB anyway).
When is it not so great? For images that are over or under exposed, a .tiff is much more limited in recovering those tones where a camera raw file is much more capable.

There are so many other file formats out there that we work with as retouchers, these three are what I always come back to for my most capable workflows.