--- id: "en/preview-annotation-review" title: "Preview, annotate and review" language: "en" description: "BabelViewer, annotation, hand drawing, voice annotation, version comparison and review collaboration." canonical_url: "https://www.babel.cc/public/babelwiki/en/preview-annotation-review.html" markdown_url: "https://www.babel.cc/public/babelwiki/ai/en/preview-annotation-review.md" alternates: {"en": "https://www.babel.cc/public/babelwiki/ai/en/preview-annotation-review.md", "zh": "https://www.babel.cc/public/babelwiki/ai/zh/preview-annotation-review.md"} reading_note: "文档记录不等于当前部署能力；以实际版本、授权模块与配置为准。保留原文的可选、限制及待确认说明，勿补猜接口。 / Documentation is not a guarantee for every deployment. Preserve optional-module requirements, limitations and unresolved API contracts." --- # Preview, annotate and review BabelViewer, annotation, hand drawing, voice annotation, version comparison and review collaboration. ![Document previewer](https://www.babel.cc/public/babelwiki/assets/images/preview-viewer-document.jpg) *BabelViewer opens documents in the browser and provides tools such as table of contents, zoom, print, download, annotation, sharing and layers.* ![CAD annotation tools](https://www.babel.cc/public/babelwiki/assets/images/preview-annotation-cad.jpg) *The graphic previewer supports symbols, shapes, arrows, freehand lines and annotation points on CAD, SVG, drawings and images.* ![Image freehand annotation](https://www.babel.cc/public/babelwiki/assets/images/preview-annotation-image.jpg) *The image previewer supports freehand drawing, selection, arrow annotations and color marks directly on images for design and material review.* > For related preview, search, OCR and format-processing capabilities, see [Search](https://www.babel.cc/public/babelwiki/en/search-preview.html) and [OCR Image Recognition](https://www.babel.cc/public/babelwiki/en/ocr-image-recognition.html). ## Detailed description In order to allow users to more conveniently preview files and conduct collaborative discussions while previewing files to improve collaboration efficiency, Babel has developed BabelViewer. Most file formats that can be previewed on Babel can be opened with the previewer. Babel Previewer can not only preview files, but also communicate with collaborators on file content through hand-drawing, text discussion, voice (only mobile APP supports the creation of voice annotations) and other methods. At the same time, BabelBird Previewer also supports version comparison, switching versions to view different version annotations, annotation management, approval management and other functions. ### Technical architecture - Use canvas development and multi-layer technology The previewer is developed based on Html5 Canvas technology and uses multi-layer technology to add annotation and hand-drawing layers on top of the file preview layer. It does not affect the file content but allows for annotation discussion and real-time hand-drawing. Real-time collaboration module The real-time collaboration module of the previewer ensures that the annotation discussions and hand-drawings of multiple users are displayed in real time when previewing files, which means that users can discuss issues with documents or design manuscripts while annotating. - Annotation point coordinate system positioning The Babel previewer uses coordinate system positioning to ensure that the annotation points are in the same position under different resolution screens and different browser sizes. ### Applicable file types See [Preview and transcoding](https://www.babel.cc/public/babelwiki/en/preview-transcoding.html) for the full preview format list and optional modules. All formats supported for preview support BabelViewer annotations except Excel and audio/video; optional formats require their preview modules to be enabled first. This does not establish online editing support or identical annotation tools for every format. All files that can be previewed in a flat, two-dimensional view are within PDF conversion scope, except audio/video and 3D; see [Automatic PDF conversion](https://www.babel.cc/public/babelwiki/en/automation-pdf.html). BabelBird’s deeply customized ONLYOFFICE provides Office online editing, Office comments and PDF conversion as a separate component from BabelViewer. Excel does not support BabelViewer annotations but does support cell comments in ONLYOFFICE; specific formats, modules and permissions depend on the customized deployment. See [Online editing](https://www.babel.cc/public/babelwiki/en/online-editing.html) for operations and [Automatic PDF conversion](https://www.babel.cc/public/babelwiki/en/automation-pdf.html) for batch conversion. ### Previewer type - Multi-page document previewer Supports preview of multi-page documents, such as word, PPT, PDF and other formats. For multi-page documents, it provides functions such as table of contents, zooming in, and page rotation that are suitable for multi-page documents. - Image previewer Designed for better preview images. It has functions such as eagle eye, zoom in and out, display original proportion, rotation, etc. Right-click to copy the image to the clipboard, making it easy to paste the image directly in WeChat or email. For images with transparency such as PNG, you can change the image background. - Graphic previewer Designed to preview vector graphic files such as CAD, SVG, single-page PDF, etc., it supports eagle eye, layered display, background change, mouse dragging area enlargement, and vector enlargement. You can switch the encoding mode for SVG files. - 3D previewer In order to preview the 3D file design, you can rotate, zoom in and out the 3D file with the mouse wheel, explode the image, and support annotation in 3D space. ### Comment type - Text discussion area Text discussion areas can be created in any area of the preview file (double-click to create text discussion comments). Collaborators of the file who have permission to view comments can see the comments and participate in the discussion. The annotation content is displayed in real time, and a text annotation discussion area is equivalent to a group chat for the annotation content. Supports inserting attachments for discussion, and also supports @ and other chat functions. You can set the visibility of comments, such as: only visible to company members, visible to everyone, and only visible to the commenter himself. - Text annotation Text annotation can add annotations to document content or photos. - Selected text annotation In preview modes that support text selection, select a passage to annotate it. Preview-supported Word, PPT and other formats support BabelViewer annotations, except Excel and audio/video. Comments inside the Office editor are a separate editor feature. - Special symbol insertion For manuscripts with special needs, revision symbols or welding marks (such as CAD drawings) can be inserted - Create graphic annotations It also supports the use of graphic frame selection annotations, supporting rectangles, ellipses and arrows. - Voice annotation The Babel mobile device APP can create voice annotations. Voice annotations can be viewed (listened to) on web pages and clients, but cannot be created. - Hand-drawn annotations Supports real-time drawing on manuscripts or documents. Participants can see the drawn lines in real time and mark the artist's nickname. ### Function module - Comment management module You can manage created comments and comment status, check other versions of comments, and switch to the corresponding version - Review workspace Babel can use comments during document review and display review-related panels, allowing reviewers to convey review information more accurately and conveniently. - Eagle Eye Eagle Eye can display the area of the image viewport when the image is zoomed in. - Version comparison Babel Previewer supports file comparison function and can also compare different versions of files. - File directory For files with directories (word, pdf), BabelBird also supports displaying the file directory during preview.