Batch Change Image DPI
Update the resolution metadata in multiple JPEG and PNG files without resampling their pixels. Enter a DPI value, process up to 30 files, and download copies with updated JPEG JFIF density or PNG pHYs information while width, height, image samples, and visual detail remain unchanged.
- 本地加工
- 无需帐户
- 每个文件的状态
- 免费使用
专为可靠的批量工作而打造
DPI is print-scale metadata, not extra resolution. This tool supports JPEG JFIF and PNG pHYs fields. It does not add pixels, sharpen an image, guarantee that every application honors the value, or safely rewrite proprietary metadata in unsupported formats.
Pixel data is not resampled
专为具有清晰输出证据的可重复图像工作流程而构建。
JPEG and PNG metadata support
您选择的文件保留在当前浏览器会话中。
Valid PNG CRC generation
每个队列行报告其自己的结果，而不阻塞有效文件。
Unsupported files fail clearly
可下载的输出使用与生成的字节匹配的名称和格式。
How to use Batch Change Image DPI
四步工作流程将原始文件与生成的输出分开。
- 1
添加文件
Select JPEG and PNG files.
- 2
选择设置
Enter a target value from 1 to 65535 DPI.
- 3
本地处理
Update and structurally verify each metadata field.
- 4
验证并下载
Download the ZIP and confirm print size in the destination application.
这个批处理工具的作用
DPI is print-scale metadata, not extra resolution. This tool supports JPEG JFIF and PNG pHYs fields. It does not add pixels, sharpen an image, guarantee that every application honors the value, or safely rewrite proprietary metadata in unsupported formats. Every item is handled independently, so one unsupported or damaged file does not erase successful work from the rest of the queue.
- Pixel data is not resampled
- JPEG and PNG metadata support
- Valid PNG CRC generation
- Unsupported files fail clearly
Batch Change Image DPI guide
使用这些检查来获取适合目标的输出，而不是在成功下载时停止。
Separate DPI from pixel dimensions
An image that is 3000 by 2000 pixels contains the same number of samples whether its metadata says 72, 96, or 300 DPI. The value suggests how densely those pixels should be placed on a physical page. At 300 DPI, 3000 pixels correspond to 10 inches; at 150 DPI, they correspond to 20 inches. Changing only metadata alters that suggested print scale, not the underlying detail.
How JPEG density is written
JPEG files can include a JFIF application segment with a density unit and horizontal and vertical values. The tool updates an existing JFIF segment when available or inserts a standards-shaped segment immediately after the JPEG start marker. It sets both axes to the requested dots-per-inch value and leaves the remaining compressed image bytes in their original order.
How PNG physical resolution is written
PNG expresses physical resolution with a pHYs chunk containing pixels per unit. For meters, DPI is converted to pixels per meter and rounded to the nearest integer. The tool replaces any existing pHYs chunk, inserts the new chunk after IHDR, and calculates the required CRC. Image data chunks are copied unchanged, so the pixel stream is not decoded or recompressed.
Confirm behavior in the receiving application
Some web browsers ignore DPI because CSS controls display size. Design, office, print, and publishing applications can interpret it differently, and an import dialog may override it. After download, verify the stated physical dimensions in the actual destination. If more pixels are required for the chosen print size, use a deliberate resampling workflow; changing metadata alone cannot create missing image detail.
批次质量检查表
当源集合很有价值时，从副本开始，并保留可让您将每个结果追溯到其原始结果的文件名。在处理整个队列之前测试一个小的代表性集，包括最大的文件、透明图像、肖像和风景图像。处理后，比较实际目标中的像素尺寸、格式、文件大小、透明度、文本清晰度、边缘细节和颜色。成功的浏览器状态确认该工具已完成并验证了其预期的输出结构；它不能取代编辑审查或接收平台的规则。保留下载的 ZIP 或 CSV 以及用于运行的设置，然后记录需要单独处理的异常。对于发布工作流程，还要检查描述性替代文本、权限、同意、命名约定、备份策略和缓存行为。这些步骤使可重复的批次比将每个已完成的下载视为自动准备生产更安全。
常见问题
有关格式、隐私、质量和浏览器行为的实用答案。
Does changing DPI improve resolution?
No. Pixel dimensions and image detail remain unchanged; only physical-resolution metadata is updated.
Which formats are supported?
This tool rewrites JPEG JFIF density and PNG pHYs metadata. Other formats are reported as unsupported.
Are JPEG pixels recompressed?
No. The metadata segment changes while the existing compressed image bytes are preserved.
Are PNG pixels recompressed?
No. A pHYs chunk is inserted or replaced and image data chunks are copied unchanged.
Why does a browser display the same size?
Web layout normally uses CSS pixels and often ignores print-density metadata.
Are the files uploaded?
No. Byte inspection, metadata rewriting, CRC calculation, ZIP creation, and download happen locally.
What DPI should I choose?
Use the value required by the actual print or publishing workflow, then verify physical size in that application.