JPEG — Complete Guide: 30 Years of History, How to Open, How to Make a JPG OSM Map

JPEG is a binary raster format with lossy compression that packs photorealistic images into files 5–20x smaller than PNG. A 1500×1500 pixel JPG map of Burj Khalifa at quality 85 weighs only 350 KB — six times less than the equivalent PNG, opens in any browser, messenger, email client, or navigator. The format was developed by the international ISO/IEC committee in 1986–1992 and still remains the most widespread way to transmit images in the world: 70% of all images on the internet are JPEG. For satellite imagery, photo-style maps, gallery previews, and quick map sharing via email or Telegram, JPEG has remained the baseline format for 30 years.

History: The Committee No One Closed for 40 Years

JPEG stands for Joint Photographic Experts Group — that's the name of the international committee that developed the format, not the format itself. The committee was established in 1986 under the aegis of two international organizations — ISO (International Organization for Standardization) and CCITT (predecessor of today's ITU-T). It included engineers from IBM, AT&T Bell Labs, Sony, Canon, Eastman Kodak, Mitsubishi, NEC. Gregory Wallace from IBM chaired the group.

The task was ambitious: create a standard for compressing photographic images that would work on cheap 1980s computers (8086, 286), with acceptable encode/decode speed, and visual quality close to original at compression ratio 10:1 and beyond. The group chose an algorithm based on Discrete Cosine Transform (DCT) — a mathematical transformation developed by N. Ahmed, T. Natarajan, K. R. Rao back in 1974.

The first version of the standard — ITU-T Recommendation T.81 — was published in 1992. In 1994, ISO/IEC formalized it as ISO/IEC 10918-1. In parallel, American engineer Eric Hamilton from C-Cube Microsystems developed JFIF (JPEG File Interchange Format, 1992) — a simple binary container for DCT-compressed data, which ultimately became the ".jpg" file everyone knows. JFIF was standardized as ISO/IEC 10918-5 in 2013.

Despite its age, JPEG hasn't become obsolete. The JPEG Committee remains active: JPEG 2000 (ISO/IEC 15444) appeared in 2000 (wavelet-based instead of DCT — theoretically better but didn't gain wide adoption), JPEG XS in 2018 (ultra-low-latency for professional video), JPEG XL in 2022 (ISO/IEC 18181, surpassing both JPEG and WebP in efficiency, but browser support extremely limited). None of these successors displaced classic JPEG — it remains the universal compatibility choice for any device, messenger, operating system.

License. Basic JPEG (DCT with Huffman coding) has been patent-free since 2002. Arithmetic coding (optional, rarely used) had patents that have since expired. Today writing a JPEG parser carries no legal risks. Steward — JPEG Committee (formally ISO/IEC JTC 1/SC 29/WG 1), site jpeg.org.

What's Inside a JPG File

JPEG/JFIF is a binary format consisting of markers (two-byte tags always starting with FF) and data between them. File starts with SOI (Start Of Image, FF D8) and ends with EOI (End Of Image, FF D9). Between them — a sequence of segments describing image parameters and compressed data.

Key markers. SOI — start of file. APP0 — JFIF identifier with size and DPI, or APP1 — Exif block with metadata (geocoordinates, capture date, camera model). DQT — Define Quantization Table — quantization tables controlling quality. This is the main parameter: the encoder generates DQT based on selected quality (0–100). Quality 85 gives typical DQT for web; quality 100 — nearly lossless; quality 50 — noticeable artifacts. SOF0 — Start Of Frame baseline, or SOF2 — progressive: describes image size and number of color channels. DHT — Huffman tables. SOS — Start Of Scan, after which compressed data follows. EOI — end of file.

Compression algorithm. 1) Image is converted from RGB to YCbCr — brightness separated from color, since human eye is more sensitive to brightness. 2) Chroma subsampling: Cb and Cr channels are thinned — typically 4:2:0 (half-resolution on each axis) or 4:4:4 (no thinning). 3) Image is divided into 8×8 pixel blocks. 4) DCT is applied to each block — transformation to frequency domain: low frequencies (smooth gradients) encoded precisely, high frequencies (sharp transitions) — coarsely. 5) Resulting coefficients are quantized per DQT — the main lossy step. 6) Results encoded with Huffman (or arithmetic) — final entropy compression.

Artifacts. As quality drops (≤60), characteristic JPEG artifacts appear: blockiness (visible 8×8 block boundaries), ringing (halos around sharp lines), color bleeding. For maps this is especially noticeable on street labels and thin metro lines — text becomes fuzzy, colored fringes appear.

Progressive JPEG. Optional mode where the file is organized as several "passes" from coarse to fine. When loading over slow connection, the picture appears immediately at low quality and gradually refines. Files are 5–10% larger than baseline JPEG. Good for web, especially mobile.

Five Roles for JPG Map Users

Travel blogger and journalist. JPG is shipped as one file to Telegram, Instagram, Twitter/X. Size 200–500 KB — standard for social media: doesn't burden readers' mobile traffic, loads in a second. If the blogger reviews a city — JPG maps of districts paired with travel photos. PNG would consume 2 MB per map — interfering with fast publication.

Email marketer. Office map in email signature, event map in newsletter, branch location map in commercial proposal. Email clients (Gmail, Outlook, Apple Mail) often block large embedded images — JPG at 200–400 KB passes without issues, PNG at 1.5 MB may be caught and ruin the impression.

Real estate agent. District map on Avito, ЦИАН (Russia), Zillow, Rightmove — all JPEG. Platforms automatically recompress everything to JPEG for hosting savings and fast mobile loading. If the agent uploads PNG, the portal resaves to JPG, sometimes losing quality — better to prepare a good JPG directly.

Mobile developer. Map snapshots cached in an Android/iOS app — JPG. An APK with 10 PNG maps grows by 20 MB; the same 10 JPGs add 2 MB. For apps downloaded by millions, this is critical — Google Play automatically reduces the rating of apps exceeding 100 MB base installer. Gallery previews — JPG.

Polygrapher (cautiously). Glossy magazines where maps serve as illustrations over photos — JPG. Continuous-tone gradient (smooth color transitions of satellite imagery) compresses ideally in JPEG and is indistinguishable from the original on glossy paper. For labels and thin lines, TIFF or PDF is better. The main thing for commercial print — convert JPG to TIFF-CMYK or PDF-X before submitting to typography, because JPG RGB and CMYK profiles differ.

Seven Programs to Open JPEG

Any modern browser. Chrome, Firefox, Safari, Edge — all render JPEG natively since 1996.

Adobe Photoshop. Paid, $20.99/mo. Main professional tool with quality slider 0–12, baseline/progressive option, Exif support, CMYK conversion.

GIMP. Free open-source. Similar features to Photoshop. Free workflow for bloggers and email marketers.

Squoosh.app. Free Google web tool. Advanced encoders: MozJPEG (15–20% smaller files at same quality), JPEG XL (experimental). Side-by-side preview.

ImageMagick. CLI: convert input.png -quality 85 output.jpg. Standard for batch site builds.

ExifTool. Free CLI/GUI for metadata. Shows and edits Exif GPS data if present.

Preview (macOS). Built-in macOS tool for basic JPEG editing.

Pros and Cons

Pros. Smallest size among universal formats: typical JPG map is 5–10x smaller than PNG. Universal compatibility 30+ years. Exif metadata (capture date, camera model, GPS coordinates if enabled). Progressive mode for slow connections. Open standard, no royalties since 2002. Streaming parsing. Efficient compression of photographs and continuous-tone images.

Cons. Lossy — each save (re-save) degrades quality. No alpha channel. Artifacts on sharp boundaries: blockiness, ringing, color bleeding especially on street labels, thin metro lines, building contours. Chroma subsampling 4:2:0 loses color on thin colored lines. Not suitable for diagrams with hatching, simple geometric illustrations. CMYK supported but RGB→CMYK via JPEG isn't best (TIFF or PDF preferable).

JPEG vs PNG, WebP, and JPEG XL

When to choose what. JPEG — for photorealistic maps (satellite, watercolor styles, relief), for web/social/email/blog, when file size matters more than perfect quality. PNG — for diagrams, maps with sharp labels, icons, transparent background. WebP — for modern web if Safari < 14 isn't a concern. JPEG XL — not production-ready yet.

How to Make a JPG Map from OpenStreetMap via osm2cdr.ru

The service renders JPG via the same QGIS layout engine as PNG, finally compressing to JPEG with configurable quality.

Step 1. Open Format Wizard. osm2cdr.ru, choose JPG from "Raster." Direct link /?format=jpg.

Step 2. Outline the area. Catalog thumbnail — 200×200 m (~50 KB). Article illustration — 500 m – 2 km (200–600 KB). A3 print — 2–5 km (1–3 MB).

Step 3. Style. Photo-style options work especially well: satellite, topo, vintage. Sharp-edge styles (blueprint, monochrome) look better in PNG.

Step 4. Quality. Default — 85, industry sweet spot, default in the renderer's image_exporter. Social media — 75–80. Print — 95. Quality 100 wastes space; use PNG. PRO tier supports 60–100 range.

Step 5. DPI and size. 72 for web/social, 150 universal, 300 for print up to A4.

Step 6. Launch export. 8–60 seconds. JPG renders slightly faster than PNG due to smaller output.

Step 7. Download and publish. Ready for Telegram, Instagram, email, corporate site. Run through Squoosh.app or convert -strip for extra 5–10% optimization.

Gotchas and Tips

Never re-save JPG many times. Each open/save cumulatively degrades quality. After 5 cycles, even quality 95 is noticeably worse than original. Workflow: save master as PSD or PNG, do edits on master, export to JPG only final version.

4:4:4 vs 4:2:0 chroma subsampling. Default is 4:2:0 — maximum compression but color "smears" across thin line boundaries. For maps with colored labels (blue metro labels in standard style), use 4:4:4 — file 30% larger but color exact. Photoshop calls it "Sample All Frequencies." ImageMagick: -sampling-factor 1x1,1x1,1x1.

Quality 60 is the floor. Below 60, artifacts visible on any image. 75 — acceptable minimum for social. 85 — sweet spot. 95 — for archival and print. 100 isn't lossless, just very high quality; for lossless use PNG, JPEG XL, or TIFF.

No transparency. If map needs to overlay another layer — that's PNG. JPG is always opaque, background will be white or matte color specified.

Metadata may contain sensitive info. Photoshop by default writes author name, software version, file path on disk, sometimes GPS to Exif. Before public publication, run through exiftool -all= or convert -strip.

Baseline vs progressive. For web publication, progressive is almost always preferable — picture appears sooner on slow connections. For catalog thumbnails — baseline (faster browser decode).

FAQ

JPG or PNG for maps? JPG — for photorealistic maps (satellite, watercolor) and for social/email where size is critical. PNG — for maps with sharp lines, diagrams, transparent background.

What is JPEG quality? A 0–100 parameter controlling aggressiveness of quantization (the main lossy step). 85 — industry standard, balance of quality and size. Below 60 — visible artifacts. Above 95 — savings not justified.

Can I get transparent JPG? No, JPEG doesn't support alpha. If the source PNG has transparent background, JPG save makes it white (default) or matte color set in the encoder.

JPG vs JPEG difference? None. JPG is just the JPEG abbreviation under FAT16/DOS 1990s three-character constraints. Modern systems treat .jpg and .jpeg identically.

What is JPEG 2000 and why didn't it replace JPEG? JPEG 2000 (ISO/IEC 15444, 2000) — next standard from the same committee, wavelet-based instead of DCT. Theoretically better but didn't get browser support (only Safari) due to patent concerns and decoder complexity. Used in Library of Congress archives, digital cinema, DICOM medical imaging.

Will JPEG XL replace JPEG? JPEG XL (ISO/IEC 18181, 2022) — modern successor from the same committee. Surpasses both JPEG and WebP in efficiency, supports lossless and lossy in one format, has animation. Main obstacle — browser support: Chrome added in 2022 and removed in 2023, Firefox and Safari don't support yet. Production-ready in 2–3 years at best.

Do I need an osm2cdr subscription for JPG? No, JPG export is free. Quality 60–100 setting available on PRO tier; free tier uses default. Details at /formats/jpg/.

Related Materials

• Vector vs raster: when to choose what for maps
• Map export for printing: PDF, PNG, TIFF
• GeoTIFF and satellite imagery
• PSD and Photoshop: maps as art objects
• Map export API for developers
• PNG — complete format guide
• SVG — complete format guide
• JPG format landing on osm2cdr

Sources

• ITU-T Recommendation T.81, JPEG Baseline Specification, 1992 — itu.int/rec/T-REC-T.81
• ISO/IEC 10918-1:1994, JPEG core standard — iso.org/standard/18902.html
• JFIF 1.02 specification (Eric Hamilton, 1992) — loc.gov/preservation/digital/formats/fdd/fdd000018.shtml
• JPEG Committee official site — jpeg.org
• Wikipedia, JPEG — en.wikipedia.org/wiki/JPEG
• Library of Congress, JPEG/JFIF sustainability — loc.gov/preservation/digital/formats/fdd/fdd000017.shtml
• Google Squoosh — squoosh.app