PDF Image Inspector Online — Check Image DPI Resolution & Color Space
Check the exact DPI resolution, pixel dimensions, color space (CMYK, RGB, Grayscale), and compression of every image inside a PDF online for free.
DROP PDF FILES HERE
or browse your device to inspect embedded raster images, DPI resolutions, and CMYK color spaces
How PDF Image Inspection Works
Follow three direct steps to parse XObject image streams, calculate placed DPI resolution, and audit CMYK color spaces in memory.
Select & Load File
Select or drag your PDF document into the workspace. The file loads directly into browser RAM with zero server latency.
Audit XObject Streams
The tool scans page content operators (cm, Do) and /XObject dictionaries to calculate pixel dimensions and placed DPI.
Inspect Color & Export
Examine color spaces (DeviceCMYK, ICCBased, Indexed), inspect alpha SMasks, preview rasters, and export diagnostic logs.
Four Embedded Image Inspection Modes
Deep diagnostic auditing across placed DPI resolutions, DCT/Flate compression filters, prepress color spaces, and transparency masks.
Placed DPI Calculation
Correlates intrinsic pixel dimensions (Width, Height) with transformation matrix scale factors to compute true on-page physical DPI.
Compression Filter Analysis
Identifies DCTDecode (JPEG), FlateDecode (PNG/ZIP), JPXDecode (JPEG 2000), CCITTFaxDecode (TIFF G4), and JBIG2 stream compression.
Color Space Evaluation
Detects DeviceRGB, DeviceCMYK, DeviceGray, Indexed, and ICCBased profiles, flagging color mismatches prior to prepress platemaking.
Soft Mask (SMask) Auditing
Inspects secondary /SMask grayscale image streams representing variable 8-bit alpha channels for transparent PNG and vector cutouts.
Utilvo In-Browser vs Cloud Image Extractors
Why client-side in-memory raster inspection guarantees true physical DPI calculations, CMYK fidelity, and absolute data privacy.
| Feature | Utilvo In-Browser | Cloud Image Extractors |
|---|---|---|
| Physical Placed DPI Calculation | Correlates pixel dimensions with transformation matrices (/cm) in RAM | Displays pixel dimensions only without calculating actual on-page placed DPI |
| Prepress CMYK & Spot Color Auditing | Inspects DeviceCMYK and embedded ICC profiles without converting to RGB | Forcibly converts CMYK rasters to sRGB for web preview, ruining color accuracy |
| Transparency & SMask Resolution | Extracts /SMask grayscale alpha stream objects and reconstructs 32-bit RGBA | Flattens transparency against white backgrounds or discards alpha masks |
| Compression Filter Verification | Detects DCTDecode, FlateDecode, JPXDecode, and CCITTFaxDecode pipelines | Re-encodes all extracted images as lossy JPEG, altering native compression |
| Zero-Persistence Local RAM Sandbox | 100% in-browser WebAssembly memory execution with zero cloud storage or logging | High-res proprietary artwork and medical scans stored on cloud server queues |
How Effective Image DPI Is Calculated from PDF Transformation Matrices
How our client engine parses XObject dictionaries, computes placed dimensions, and resolves alpha masks.
Placed DPI Mathematics & Transformation Matrices
PDF images occupy a unit square of 1x1 user space points by default. The content stream operator [a b c d e f] cm scales and positions the image. Placed DPI is calculated as (Pixel Width / (a / 72)) horizontally and (Pixel Height / (d / 72)) vertically.
Soft Mask (SMask) Alpha Channels
Unlike web PNGs with interleaved RGBA pixels, PDF stores transparency as an independent grayscale XObject under the /SMask dictionary key. The engine reconstructs the composite image by blending color and mask data in a canvas buffer.
DeviceCMYK Prepress Color Spaces
Commercial print documents use 4-channel DeviceCMYK rasters. To display these rasters accurately on sRGB computer monitors, the engine maps subtractive cyan, magenta, yellow, and black ink densities to RGB color space.
Client-Side Privacy Guarantee
All image extraction, DPI calculations, and color space inspections execute 100% inside your web browser sandbox. No high-resolution artwork, photos, or confidential documents are ever transmitted across external networks.
Verifying 300 DPI Resolution & CMYK Color Mode for Print
Follow these recommended checks before sending PDF files to commercial printing facilities.
Verify Placed DPI Thresholds
Ensure continuous-tone color photos achieve at least 300 DPI (and line art 1200 DPI) at placed dimensions for sharp printing.
Confirm Prepress Color Spaces
Check that editorial artwork uses DeviceCMYK or calibrated ICC profiles rather than uncalibrated RGB color spaces.
Inspect Alpha SMasks
Verify that transparency cutouts and dropshadows use valid /SMask dictionaries to avoid rendering box artifacts.
Detect Lossy Compression
Audit DCTDecode compression quality levels to ensure critical product graphics show no visible JPEG blocking artifacts.
PDF Image Stream Filters vs Specification Standards
Comparing compression algorithms, color space support, and alpha mask handling across ISO 32000 specifications.
| Stream Filter | Standard | Compression Profile | Color Space Support | Role | Best Use Case |
|---|---|---|---|---|---|
| Unprocessed PDF Input | ISO 32000-1/2 | Multiple raw XObject streams | Raw binary stream in RAM | Source of this tool | Commercial offset print audits, prepress preflight, resolution verification |
| Image Audit JSON Report | JSON / ISO 32000 | Comprehensive raster telemetry | JSON diagnostic dump | Target of this export | Automated CI/CD prepress pipelines, image asset inventory, archival compliance |
| DCTDecode (JPEG) | ISO/IEC 10918-1 | Lossy DCT frequency quantization | RGB, CMYK, Gray | Continuous tone stream | Photographic plates, high-res portraits, full-bleed catalog covers |
| FlateDecode (Deflate) | RFC 1951 / zlib | Lossless LZ77 + Huffman coding | RGB, CMYK, Gray, Indexed | Lossless raster stream | Screenshots, company logos, technical diagrams, 8-bit alpha SMasks |
| JPXDecode (JPEG 2000) | ISO/IEC 15444-1 | Wavelet-based lossy or lossless | Multi-channel + native alpha | Advanced raster stream | High-end fine art prints, archival document preservation, medical imaging |
| CCITTFaxDecode | ITU-T Recommendation T.4/T.6 | 1-bit bi-level run-length coding | DeviceGray (1-bit B&W) | Monochrome scan stream | Archival scanned legal briefs, patent drawings, facsimile records |
Frequently Asked Questions
Learn how client-side image inspection calculates real-world DPI, verifies CMYK/RGB color spaces, and extracts embedded raster XObjects.
1What image metadata and properties does the inspector extract?
It audits pixel dimensions (width x height), calculated print DPI, native color spaces (DeviceRGB, DeviceCMYK, DeviceGray, ICCBased), bit depths, and compression filters (DCTDecode, FlateDecode, JBIG2Decode).
2Can I preview and download embedded raster images?
Yes. The tool renders high-resolution previews of extracted XObject image streams and lets you download individual images or full archives in PNG or JPEG format.
3How does the tool calculate real-world effective DPI?
It compares the intrinsic pixel resolution of the embedded image stream with the physical dimensions of the bounding transformation matrix (cm operator) on the PDF page.
4Are my uploaded PDF documents processed securely?
Yes. Image stream decompression, metadata parsing, and pixel rendering execute 100% in your browser's WebAssembly sandbox with zero server uploads.
5Why is checking PDF image color spaces important for printing?
Commercial offset printing requires DeviceCMYK with embedded ICC profiles. Identifying uncalibrated RGB or low-DPI images prevents muddy colors and blurry print results.
6How does the inspector handle transparent PNGs and SMask channels?
The tool automatically detects Soft Mask (/SMask) image dictionaries and composite alpha channels, reconstructing full transparency into downloadable PNG format.
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