Mild sharpen
job_5e3f612ef3e24de2Odd matrix, modest amount.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -vf "unsharp=5:5:1.0" -t 5 out.mp4video filter
The FFmpeg unsharp filter
Sharpens or blurs using an unsharp mask with configurable matrix size.
3 of 3 variants measured Measured 2026-08-20
The part that catches people
The matrix size arguments must be ODD. Passing an even number is rejected outright. And a negative amount blurs rather than sharpens, which is the documented way to soften with this filter.
Measured, not described
Every row below is a real job. The same 1280x720 five-second H.264 source went through each variant, so the numbers are comparable to each other and to every other filter page on this site. Encode time is the FFmpeg step on its own, separated from the download and the upload.
| Variant | Encode | Output | Cost |
|---|---|---|---|
| Mild sharpen | 1022 ms | 505.8 KB · 1280x720 | $0.0025 |
| Strong sharpen | 1177 ms | 656.5 KB · 1280x720 | $0.0027 |
| Blur via negative | 1132 ms | 433.5 KB · 1280x720 | $0.0026 |
The fastest variant here is not the smallest. Mild sharpen finished the encode in 1022 ms, while Blur via negative produced the smallest file at 433.5 KB. Which one matters depends on whether you are paying for compute or for storage.
The exact commands
Strong sharpen
job_0747a9c80f5c4825Larger matrix, heavier amount. Watch for ringing.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -vf "unsharp=7:7:2.0" -t 5 out.mp4Blur via negative
job_c1b6e2bbaf424d8dNegative amount inverts the mask into a blur.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -vf "unsharp=5:5:-1.0" -t 5 out.mp4How these numbers were produced
Each variant was submitted to the Rendobar API as an ffmpeg job against the same public source file, and the response was recorded verbatim. Encode time is the API's own per-step timing for the FFmpeg step. Output size is the byte count of the file the job produced. Cost is what the job was actually billed.
Nothing here was estimated, and the whole set is re-runnable, so if a figure looks wrong it can be checked rather than argued about. The 72 variants behind this filter reference cost $0.193082 in total to measure.
Frequently asked questions
What does the FFmpeg unsharp filter do?
Sharpens or blurs using an unsharp mask with configurable matrix size.
What is the most common mistake with unsharp?
The matrix size arguments must be ODD. Passing an even number is rejected outright. And a negative amount blurs rather than sharpens, which is the documented way to soften with this filter.
How long does unsharp take to run?
On a 1280x720 five-second H.264 source, the fastest variant on this page (Mild sharpen) spent 1022 ms inside FFmpeg. That figure is the encode step alone, measured separately from the download and the upload, so it is the filter's own cost rather than the round trip.
Do I need FFmpeg installed to use unsharp?
Not with Rendobar. Every command on this page ran through the Rendobar API against a URL, with no local FFmpeg install and no server. The job id next to each row is the real job that produced the numbers.
Other filters, measured the same way
scale Resizes video to a target width and height, with optional aspect-preserving arithmetic. crop Cuts a rectangle out of each frame, positioned from the top-left corner. fps Resamples video to a constant frame rate by duplicating or dropping frames. transpose Rotates video by 90 degree steps, optionally flipping as it goes. pad Adds bars around the frame to reach a target size without cropping the picture.
Run unsharp without installing FFmpeg
Every command on this page ran through the API against a URL. No binary, no server.