- Drop your photographs into the upload tray or hit Browse to pick them from disk.
- From the Convert To menu, pick the destination container — JPG for general use, WebP if your audience is on a modern browser.
- Slide the quality control to 80 for everyday work or 90 for portrait-heavy sets; values above 95 are usually wasted bytes.
- Press Convert. The Gilhe London server pushes the file through Imagick and hands you a download link.
- For multi-image batches, the “Download Zip” bundle is one click away.
Technical handbook from the Gilhe team
The following sections extend the quick steps above with the engineering detail we would give to a colleague. Gilhe Image Converter is built around speed-first, low-friction format conversions; every recommendation below is written against real workloads, not generic marketing copy. If anything conflicts with your in-house policy, your policy wins — but if you are starting from scratch, this is the baseline we ship in production.
Format selection matrix
JPG is the default interchange format for continuous-tone photography on the web and in most CMS pipelines. It does not support transparency; semi-transparent PNGs flattened to JPG acquire a flat colour background (usually white). PNG is lossless and should be chosen when you have hard edges, UI screenshots, diagrams or alpha channels. WebP offers both lossy and lossless modes and typically beats JPG on byte size at the same perceived quality; Gilhe prefers WebP for outbound web assets when the destination stack supports it. GIF should be reserved for legacy animation or extremely constrained environments — for static graphics, PNG or WebP lossless is almost always superior. BMP and TIFF are archival and print-interchange formats; they produce large files and are inappropriate for browser delivery but excellent for hand-off to a pre-press partner. HEIC is the default capture format on many modern phones; converting HEIC to JPG or WebP is the standard path before uploading to web platforms that do not yet parse HEIC reliably. PDF is a container: raster pages embedded in PDF through Gilhe are suitable for proofing and lightweight document assembly, not for replacing a professional pre-press workflow.
Colour profiles and metadata
Our Imagick-based pipeline reads embedded ICC profiles where present and aims to produce outputs that decode predictably in sRGB-centric browsers. Wide-gamut sources (Adobe RGB or ProPhoto) may be perceptually compressed when targeting sRGB — that is expected behaviour, not a bug. EXIF orientation tags are honoured on read. IPTC copyright and caption fields are preserved on formats that support embedded metadata in our build configuration; if you rely on a specific metadata block for legal reasons, spot-check the output in exiftool after first use.
Quality slider semantics
The quality control affects only lossy codecs (JPG, WebP lossy). It maps to encoder-specific quantisation tables — not to a literal “percentage of pixels kept”. A setting of 80 is the Gilhe recommended default for web photography; 90 for hero images and portraits where banding is more costly than bytes; 95+ should be rare and usually indicates that the asset should have stayed in PNG or TIFF until final delivery. Lossless targets ignore the slider by design.
Security and retention
Uploaded files are written only to a quarantined temporary directory with regenerated names. Path traversal attempts are rejected at validation. MIME sniffing via finfo is combined with extension checks. Working files and derivatives are deleted automatically within twenty-four hours. We do not train models on your content, sell thumbnails, or fingerprint files for advertising. If your organisation requires a Data Processing Agreement, contact hello@gilhe.com with your jurisdiction and volume.
When Gilhe conversion is the wrong tool
Do not use the browser converter for medically regulated imaging, forensic evidence chains, or mission-critical print colour proofing without independent validation. Do not batch confidential material from an unmanaged device on a shared network without VPN discipline. For anything requiring CMYK separations, spot channels, or ink-limit profiles, stay in desktop pre-press software until the final rasterisation step.