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Image glossary

The words behind a rejected upload

One hundred photo editing terms, each defined in plain words and filed under the part of the job it belongs to.

100 terms8 groupsSources linked

The short answer

This glossary defines the hundred words that decide whether a photo clears an upload form, from alpha channel and chroma subsampling to sRGB, PPI and image matting. Each entry gives the definition first, then the quick facts, then the mistakes people make. Every one links the specification or documentation it was read from.

How to use it

  • Every entry opens with the definition on its own, so you can stop reading as soon as you have the answer.
  • Aliases are printed next to each term below, so a browser find on the word you know lands on the entry you need.
  • The eight groups follow the path a photo takes, from the edit through the file format to the print.
  • Photomop is a photo studio that runs on your own device, and each entry links the tools that do the job it describes.

Jump to a group

21 terms

Editing and retouching

The words for what you do to a photo: masks, mattes, cut-outs, blur, sharpening.

12 terms

Resolution and scaling

Pixels, ratios and what happens to them when an image is made bigger or smaller.

18 terms

File formats

PNG, JPEG, WebP, AVIF, HEIC and the rest, plus the metadata they carry.

  • AVIF

    .avif, av1 image file format

  • BMP

    .bmp, bitmap, windows bitmap

  • EXIF

    exif data, exchangeable image file format, photo metadata

  • Geotag

    gps metadata, location data in photos, geotagging

  • GIF

    .gif, gif file, animated gif

  • HEIC

    heif, .heic, high efficiency image container

  • ICO

    .ico, icon file, favicon file

  • Image metadata

    photo metadata, embedded metadata, iptc

  • JFIF

    .jfif, jpeg file interchange format

  • JPEG

    jpg, .jpg, .jpeg

  • Orientation tag

    exif orientation, rotation tag, sideways photo

  • PDF image

    image in pdf, pdf photo, image to pdf

  • PNG

    portable network graphics, .png, png file

  • Raster image

    bitmap image, pixel image, raster vs vector

  • RAW image file

    raw file, camera raw, cr3

  • SVG

    .svg, scalable vector graphics, vector file

  • TIFF

    .tif, .tiff, tagged image file format

  • WebP

    .webp, webp image

9 terms

Compression

How a photo is squeezed to fit an upload limit, and what it costs to squeeze it.

14 terms

Colour

Profiles, spaces, gamut and bit depth: why a photo shifts colour on somebody else's screen.

  • Bit depth

    colour depth, bits per channel, 8-bit vs 16-bit

  • Colour gamut

    color gamut, gamut, gamut range

  • Colour profile

    color profile, embedded profile, image profile

  • Colour space

    color space, colourspace, working space

  • Colour tag

    color tag, colour space tag, untagged image

  • Contrast

    image contrast, tonal contrast, levels

  • Gamma

    gamma correction, transfer function, gamma 2.2

  • HDR

    high dynamic range, hdr image, hdr photo

  • Hex colour

    hex code, hex color, #ffffff

  • ICC profile

    icc, international color consortium profile, .icc

  • RGB

    red green blue, rgb colour model, rgba

  • Saturation

    colour intensity, vibrance, chroma

  • sRGB

    standard rgb, srgb colour space, iec 61966-2-1

  • White balance

    colour temperature, wb, kelvin

12 terms

AI and on-device processing

Segmentation, matting, diffusion and the runtimes that put them on your own device.

12 terms

Photo types and platforms

Listing images, hero shots, thumbnails, flat lays and the other named jobs a photo does.

2 terms

Print

The two numbers that decide whether a screen file survives a printer.

  • CMYK

    cmyk colour, four colour process, print colours

  • DPI

    dots per inch, print dpi, 300 dpi

About this glossary

How the glossary is written

Where the definitions come from, how long they run, and what the groups mean.

What is this glossary for?

It defines the words that decide whether a photo clears an upload form: alpha channel, chroma subsampling, sRGB, PPI, matting and about ninety-five more. Each entry states the definition first, then the detail that changes what you export, then the mistakes people make with it.

How long is each entry?

Short. Most run to a definition, a table of quick facts, two to five sections and a handful of questions. A definitional page earns its place by answering fast, so none of them pad the answer out to hit a word count.

Where do the definitions come from?

Specifications and vendor documentation, linked at the foot of every entry: the W3C PNG specification, MDN, the ICC, the JPEG standard, and the platform help pages where the term is a platform rule rather than a technical one. Every entry lists what it was read from.

How are the terms grouped?

Into eight groups that follow the path a photo takes: what you do to it, how big it is, what you save it as, how hard it is squeezed, what colour it comes out, what runs the edit, where it ends up, and what happens if it is printed.

Do I need any of this to use Photomop?

No. Photomop is a photo studio that runs on your own device, and the tools carry the presets so you do not have to know what a colour profile is to hit an sRGB requirement. The glossary is here for the day a platform rejects a file and only tells you a word.

How often does the glossary change?

Every entry carries the date it was last revised, and the format entries move most, because AVIF, HEIC and WebP support changes with each browser release. A definition older than the standard it describes is the failure mode we watch for.

Keep reading

Elsewhere on Photomop

Or just fix the file

Most of the words here exist because a platform rejected something. Resize, crop, compress and convert run on your own device at full resolution with no watermark, and the marketplace guides carry the exact numbers each platform asks for.

Open the toolboxPlatform requirements