How to Fix Errors in 4K Image Compressor
4K Image Compressor is a desktop application for Windows, macOS, and Linux that enables you to reduce the size of your images and convert them to other formats. While the application is fully equipped with everything needed for lossless and lossy file compression and conversion to different formats, we must note that not all files can be successfully compressed and/or converted without significant quality loss and other problems.
Some files can’t be efficiently compressed — not because of a malfunction in 4K Image Compressor, but because they already exist in a highly compressed state. These files use efficient compression techniques, and further compression may not result in a significant reduction in file size.
Some formats, on the contrary, were created specifically for lossless use and are almost incompressible — PNG is a prime example. Because of these and other peculiarities, you may experience errors at some points while using the application.
For quick solutions, see the most common issues below; for more background and technical explanations, refer to the FAQ on compression and conversion.
Common Errors and Solutions
“Image file required”
Reason: This error occurs when you upload a file in a format that isn’t supported by the application.
Solution: Make sure that you upload your file in a suitable format. 4K Image Compressor currently supports the following formats: JPEG, PNG, WEBP, HEIC, HEIF, PDF, BMP, JFIF, RAW, GIF, ICO, SVG, and EPS.
“Impossible to compress to the selected size”
Reason: This error occurs only with lossy compression when optimizing the file size. In particular, this happens when the target file size is too small and the application can’t reach it.
Solution: The easiest solution is to compress files in the Same as Input mode, set the optimization to File Size, and the value as Percent within an adequate range. This way, there’s no conversion, and you don’t have to calculate the target size every time depending on the input file.
As an alternative, you can learn a bit about formats and how they work, and keep that in mind as you compress. For example, it’s not technically possible to upload a 1MB JPEG file, set the output format to PNG, and the goal size to 200KB, and then achieve any sort of quality result.
More likely than not, you wouldn’t be able to get a decent result even if you set 1MB as the goal size. That’s because JPEG is a lossy format, whereas PNG is lossless, so it has a lower compression rate in comparison to lossy formats but offers higher quality.
“Suboptimal result. Try using different compression settings”
Reason: This error occurs when the file size resulting from compression is larger than the original file. Yes, this is possible due to the peculiarities of formats. It usually, but not exclusively, happens when converting from JPEG and WEBP (lossy) to PNG (lossy/lossless), from JPEG to WEBP (lossless), and from WEBP (lossless) to PNG (lossless).
Solution: As in the previous case, you can either compress files in default mode (Format: Same as Input; Optimization: Auto with basic settings), or, when modifying the settings, take into account the parameters of the original file, how much it can be compressed, and whether it makes sense to convert to another format.
It’s not recommended to convert lossy formats like JPEG to lossless formats such as PNG, as it will only result in larger file sizes without any improvement in image quality.
Can't access the output file
Reason: Compression completed, but for some reason, the resulting file couldn’t be created.
Solution: The chance of encountering this error is extremely low, as it’s very rare. If it does occur, try uploading the file again. If the error happens again, contact support to troubleshoot the issue.
