When you buy a 4K disc instead of a Blu-ray or DVD of a title, you may be doing so under the assumption that you’re getting improved picture quality for your money. Often this is the case. Technically, 4K discs do generally offer superior video quality when compared to previous physical media formats.

That said, if you’re on the fence about spending extra money to get a 4K version of a movie or a series, you may want to research that particular disc’s reputation before committing to a purchase. There are actually instances in which the 4K versions of certain titles look less impressive than their Blu-ray counterparts. These are just a few reasons that can happen.

Digital noise reduction can have unwanted effects

Attempts to improve image quality don’t always yield the best results

One of the most famous cases of a 4K upgrade actually looking worse than the previous Blu-ray version is Terminator 2. This is an instance in which efforts to improve the visuals of a film actually end up having the opposite effect.

For example, when preparing a movie for 4K, a studio or label may try to get rid of film grain and similar quote-unquote imperfections through digital noise reduction.

The problem is too much digital noise reduction can remove more than just grain. It can sometimes remove image details. While the new 4K version of the film may not have the same grainy appearance as the earlier version, it could look so smooth as to appear unnatural.

Keep in mind that some people also prefer a little film grain. This is similar to how some vinyl fans actually enjoy the pops and crackling noises associated with the format. If you like older movies to have that grainy quality, a 4K “upgrade” might actually be anything but, at least from your perspective.

The 4K master was inferior to begin with

The source material plays a big role in a 4K disc’s quality

Studios don’t always source 4K masters or restorations using the same masters or restorations they used for their Blu-rays. It’s possible that a new 4K version of a title will be generated via an inferior version when compared to the master or restoration that was used to generate the Blu-ray version.

This may be more likely if a film is old and has thus undergone a substantial number of restorations or transfers.

Again, the best way to guard against buying an inferior 4K disc in these circumstances is to simply do your research and find out whether this particular issue applies to a given disc you are thinking about buying.

High dynamic range grading can make images look unpleasant

HDR results in colors that look overwhelming

As with digital noise reduction, high dynamic range grading, or HDR grading, may be a way of theoretically improving an image that unfortunately has the opposite effect when actually applied.

The point of HDR grading is to allow the images on a screen to offer a greater range of brightness and color than was previously possible. However, the results of this can be mixed.

For example, sometimes highlights might become so bright that they look fake, or the colors may simply be altered in such a way as to no longer properly reflect the original vision of the cinematographer.

In either case, just because something is an upgrade, that doesn’t necessarily mean it’s always better.

Sometimes a film just doesn’t benefit much from a 4K restoration or upgrade

Not every title needs the 4K treatment

There are cases in which a 4K version of a film may look about as good as the Blu-ray version. In these instances, even if the 4K version doesn’t exactly look worse, it still doesn’t make sense to spend additional money on a format that doesn’t offer any additional benefits.

There are various reasons why some movies don’t benefit very much from 4K. For example, again, older movies may only be able to achieve a certain degree of visual quality. The same can be said for movies that originally used significant optical effects and general low-quality elements.

It’s also critical to understand that not every 4K disc is derived from a native 4K source. For some 4K discs, the source material consists of 2K digital intermediate transfers. While these discs may ultimately offer some improvement over previous Blu-ray and DVD versions, the extent of that improvement may not live up to your expectations. Again, this might be a case where you end up feeling you spent more money on a disc that wasn’t worth it.

All that said, as a dedicated cinephile and physical media enthusiast, I’m certainly not saying 4K versions of movies aren’t worth it. Most of the time, a 4K disc will absolutely represent an improvement over what came before. However, to avoid wasting your cash, you should also know that there are exceptions. Understanding why these exceptions occur can help you make wiser choices when purchasing titles for your physical media collection. While you’re at it, you may also want to research whether the disc versions of any titles you’re considering buying have negative reputations due to factors like glitches. If you’re a physical media collector, a little bit of research can make a big financial difference.