Pixel Quality Count 25m 2.0.0

The Pixel Quality (PQ) product is an assessment of whether an image pixel represents an un-obscured, unsaturated observation of the Earth's surface and whether the pixel is represented in each spectral band. The PQ product allows users to produce masks which can be used to exclude pixels which don't meet various quality criteria from further analysis. The capacity to automatically exclude such pixels from analysis is essential for emerging multi-temporal analysis techniques that make use of every quality assured pixel within a time series of observations.The PQ count (PQ-COUNT) product is a count of how many times a pixel contains a clear observation of the earth's surface (land or sea) at a particular location for a particular period of time. PQ-COUNT is available for the following epochs:PQ-COUNT-SUMMARY, this contains a count of all observations contained within the DEA (from 1987 to the most up to date imagery available);PQ-COUNT-ANNUAL-SUMMARY, this contains a count of the number of observations acquired in each full calendar year (1st of January - 31st December) from 1987 to the most recent full calendar year;PQ-COUNT-SEASONAL-SUMMARY, this contains a count of the number of observations acquired within each calendar season (DJF, MAM, JJA, SON). This product is available for the most recent 8 seasons.

像素质量（Pixel Quality，PQ）产品用于评估图像像素是否为地球表面的无遮挡、未饱和观测结果，以及该像素是否在所有光谱波段中均有有效记录。该PQ产品可支持用户生成掩膜，用于剔除不符合各类质量标准的像素，以开展后续分析。自动剔除不合格像素的能力，对于新兴的多时相分析技术至关重要——这类技术需充分利用观测时间序列中所有经过质量保障的像素。

像素质量计数（PQ Count，PQ-COUNT）产品用于统计特定时段内、特定位置的像素对地球表面（陆地或海洋）的有效观测次数。PQ-COUNT 包含以下三类统计产品：
PQ-COUNT-SUMMARY：统计DEA数据集（1987年至今的所有可用影像）内的全部观测次数；
PQ-COUNT-ANNUAL-SUMMARY：统计1987年至最近一个完整自然年（1月1日至12月31日）内每个完整自然年度的观测次数；
PQ-COUNT-SEASONAL-SUMMARY：统计每个自然季节（DJF、MAM、JJA、SON）内的观测次数，该产品仅提供最近8个季节的统计结果。