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.
- ដំណើរការក្នុងស្រុក
- មិនចាំបាច់មានគណនីទេ។
- Per-file status
- ប្រើដោយឥតគិតថ្លៃ
Built for dependable batch work
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
Built for repeatable image workflows with clear output evidence.
JPEG and PNG metadata support
Your selected files remain in the current browser session.
Valid PNG CRC generation
Each queue row reports its own result without blocking valid files.
Unsupported files fail clearly
Downloadable output uses names and formats that match the generated bytes.
How to use Batch Change Image DPI
A four-step workflow keeps the original files separate from generated output.
- ចេក
Add files
Select JPEG and PNG files.
- 2
Choose settings
Enter a target value from 1 to 65535 DPI.
- បី
Process locally
Update and structurally verify each metadata field.
- ៤
Verify and download
Download the ZIP and confirm print size in the destination application.
What this batch tool does
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
Use these checks to get output that fits the destination rather than stopping at a successful download.
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.
Batch quality checklist
Start with copies when the source collection is valuable, and keep filenames that let you trace every result back to its original. Test a small representative set before processing the full queue, including the largest file, a transparent image, a portrait, and a landscape image. After processing, compare pixel dimensions, format, file size, transparency, text sharpness, edge detail, and color in the actual destination. A successful browser status confirms that this tool completed and verified its expected output structure; it does not replace editorial review or the receiving platform’s rules. Keep the downloaded ZIP or CSV with the settings used for the run, then record exceptions that need individual treatment. For publishing workflows, also check descriptive alternative text, rights, consent, naming conventions, backup policy, and cache behavior. These steps make a repeatable batch safer than treating every completed download as automatically ready for production.
សំណួរដែលគេសួរញឹកញាប់
Practical answers about formats, privacy, quality, and browser behavior.
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.