# Job: Downsample Particles

## **Description**

Downsample particles and save them with smaller box sizes and optionally apply filters.

![Downsample particles outputs depicting original and processed particles](/files/Dg4MMpDxetLn8l4jJCz2)

## **Input**

* Particles (`blob` required; `alignments2D` and `alignments3D` optional)

## **Common Parameters**

* `Crop / pad to box size (pix)`: Crop in real space to this size before downsampling. If this number is larger than the input size, each particle will be padded with its mean pixel value
* `Desired approx. pixel size (A)`: If set, the output particles will be downsampled to have approximately the specified pixel size. Only this parameter *or* `Fourier crop to box size (pix)` should be set, not both.
* `Fourier crop to box size (pix)`: If set, the output particles will be downsampled to have the specified number of pixels in each dimension. Only this parameter *or* `Desired approx. pixel size (A)` should be set, not both.
* `Lowpass resolution (A)`: Resolution of corner frequency in Angstroms
* `Recenter using aligned shifts`: Activate this parameter to recenter the particles based on their shifts.
  * Particles will only be recentered if this is true, and `alignments3D` or `alignments2D` are connected.
  * Note that `alignments2D` will be used for recentering only if `alignments3D` are unavailable.
  * [Job: Volume Alignment Tools](/processing-data/all-job-types-in-cryosparc/utilities/job-volume-alignment-tools.md) may be used to change the geometric center of a particle stack prior to downsampling and recentering, for the purpose of subparticle cropping.
* `Save results in 16-bit floating point:` Saves the output particles in [float16 format](/processing-data/tutorials-and-case-studies/tutorial-float16-support.md) (CryoSPARC v4.4+).

## **Output**

* Downsampled Particles

## Common Next Steps

* Running *2D Classification, 3D Classification, 3D Variability Analysis or Heterogeneous Refinement* on downsampled particles. To refine a structure using the full particle resolution, you can reference the original (non-downsampled) particle data using an [input-group override as described in this tutorial](https://guide.cryosparc.com/processing-data/tutorials-and-case-studies/job-builder-tutorial#use-case-downsampled-particles).


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