Ground truth for Neue Zürcher Zeitung black letter period

The Neue Zürcher Zeitung (NZZ) has been publishing in black letter from its very first issue in 1780 until 1947. From this time period, we randomly sampled one frontpage per year, resulting in a total of 167 pages. We chose frontpages because they typically contain highly relevant material and because we want to make sure not to sample pages containing exclusively advertisements or stock information. During certain periods, the NZZ was published several times a day, and there were supplements, too. Due to incomplete metadata, the sampling included frontpages from supplements. We then manually corrected the pages, so it can be used as a ground truth to improve the OCR of black letter in historical newspapers.《新苏黎世报》（Neue Zürcher Zeitung，NZZ）自1780年创刊至1947年期间，始终采用黑体活字（black letter）排版。在此时间跨度内，我们每年随机抽取一份头版，最终共获得167页样本。选取头版作为样本的原因在于：一方面，头版通常刊载极具分量的核心内容；另一方面，我们希望规避仅包含广告或证券行情信息的版面。在部分历史时期，《新苏黎世报》每日发行多个版本，且附带各类副刊。由于元数据不全，本次抽样纳入了副刊的头版。随后我们对所有样本版面进行了人工校正，该数据集可作为基准真值（ground truth），用于优化历史报纸中黑体活字的光学字符识别（Optical Character Recognition, OCR）效果。