Evals / image / Size and compression

Hit a size limit without resizing

earth.jpg is 6MB. Get it under 500KB without changing its dimensions, as small.jpg.

normalsinglesmokedeft image compress

The task

The reference answer shows the job can be done with deft. It is not an agent run.

deft image compress earth.jpg --target-size 500KB -o small.jpg

Input

earth.jpg 6.2 MB · 3000x3002
earth.jpg

Reference output

small.jpg 492.3 KB · 3000x3002
small.jpg
How a result is judged (3 checks)
  • max_bytes: file = "small.jpg", bytes = 512000
  • image: file = "small.jpg", width = 3000, height = 3002
  • image_similar: file = "small.jpg", to = "earth.jpg", max_difference = 6

Runs

CodexWithout deftPassed2026-11-07

Time
18s
New tokens
4.5k
Total input
68.3k
Output tokens
0.5k
Commands
4
Failed
0

Trace

  1. I’ll inspect the image dimensions and available image tools, then compress it into `small.jpg` in the current directory and check the resulting size.

  2. pwd && ls -lh earth.jpg && file earth.jpg
    output
    -rw-r--r--@ 1 user  staff   6.2M Nov  5 21:11 earth.jpg
earth.jpg: JPEG image data, JFIF standard 1.02, resolution (DPI), density 300x300, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=7, orientation=upper-left, xresolution=98, yresolution=106, resolutionunit=2, software=Adobe Photoshop CS Windows, datetime=2005:05:13 13:09:04], baseline, precision 8, 3000x3002, components 3
  3. command -v magick; command -v convert; command -v cjpeg; command -v python3; python3 -c 'import PIL; print(PIL.__version__)' 2>/dev/null || true
    output
    ~/opt/anaconda3/bin/cjpeg
/usr/local/bin/python3
12.2.0
  4. python3 - <<'PY' from PIL import Image im = Image.open('earth.jpg') print(im.size, im.mode) for q in (90,85,80,75,70,65,60): im.save('small.jpg', 'JPEG', quality=q, optimize=True, progressive=True) import os n=os.path.getsize('small.jpg') print(q, n) if n < 500_000: break PY ls -lh small.jpg
    output
    (3000, 3002) RGB
90 1555573
85 1211006
80 1020580
75 877520
70 793509
65 712810
60 649009
-rw-r--r--@ 1 user  staff   634K Nov  7 00:48 small.jpg
  5. python3 - <<'PY' from PIL import Image import os im=Image.open('earth.jpg') for q in (55,50,45,40,35,30,25): im.save('small.jpg','JPEG',quality=q,optimize=True,progressive=True) n=os.path.getsize('small.jpg') print(q,n) if n < 500_000: break PY file small.jpg && ls -lh small.jpg
    output
    55 598052
50 560626
45 520334
40 480988
small.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, progressive, precision 8, 3000x3002, components 3
-rw-r--r--@ 1 user  staff   470K Nov  7 00:49 small.jpg

  6. Created [small.jpg](small.jpg). It’s 480,988 bytes (under 500 KB) and keeps the original 3000 × 3002 dimensions.

Output

small.jpg 469.7 KB · 3000x3002
small.jpg

CodexWith deft, skill installedPassedRead the skillUsed deft2026-11-07

Time
14s
New tokens
5.3k
Total input
72.4k
Output tokens
0.3k
Commands
4
Failed
0

Trace

  1. I’ll inspect the image and use the available local image-compression workflow, preserving its dimensions and writing `small.jpg` in the current directory.

  2. cat .agents/skills/deft/SKILL.md
    output
    ---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; r
… 700 more characters
  3. deft find "compress JPEG to target file size preserving dimensions" && ls -lh earth.jpg && deft image
    output
    image compress  image -> image  Smaller file: --quality, --target-size 200KB
image resize    image -> image  Scale: --size 800x, 1920x1080, 50%
-rw-r--r--@ 1 user  staff   6.2M Nov  5 21:11 earth.jpg
deft image - commands (input -> output)
  info         image -> report      Format, dimensions, EXIF orientation, GPS
  adjust       image -> image       Change --brightness, --contrast, --saturation, --gamma
  blur         image -> image       Gaussian blur: --radius 5, or a --box region
  compress     image -> image       Smaller file: --quality, --target-size 200KB
  convert      image -> image       Change format: --to png|jpg|webp|avif|gif|tiff|bmp|ico
  crop         image -> image       Cut a region: --box x,y,w,h or --aspect 16:9
  favicon      image -> ico+png...  Website icon set: favicon.ico and PNG sizes
  flip         image -> image       Mirror: --direction horizontal|vertical
  frames       gif -> png...        Save each frame of an animated GIF as PNG
  grayscale    image -> image       Remove colour
  meta         image -> image       Read EXIF, or set --title --author --copyright --date
  montage      image... -> image    Tile images into a grid: --cols 3 --size 300x300
  ocr          image -> txt         Read the text in an image (tesseract)
  pad          image -> image       Add a border or canvas: --border 20, --size 1080x1080
  resize       image -> image       Scale: --size 800x, 1920x1080, 50%
  rotate       image -> image       Turn clockwise by any angle
… 589 more characters
  4. deft image info earth.jpg && deft image compress --help
    output
    ok image.info earth.jpg  3000x3002
width=3000 height=3002 orientation=1 has_metadata=true has_gps=false
deft image compress - Smaller file: --quality, --target-size 200KB

Usage: deft image compress <image>... [-o <image|dir>] [options]
In: image (each handled separately)   Out: image (default <name>.compressed.<ext>)
JPEG and WebP re-encode (WebP needs ffmpeg). PNG is optimised losslessly.
A file is never made larger. Missing --target-size is an error.

Options:
  --quality <n>                JPEG and WebP quality (default 75)
  --target-size <bytes>        Lower the quality until output <= this size
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft image compress photo-1.jpg -o small.jpg
  deft image compress photo-2.jpg --target-size 100KB -o tiny.jpg

Result fields: bytes_before, bytes_after, ratio, quality
Errors: TARGET_UNREACHABLE
  5. deft image compress earth.jpg --target-size 480KB -o small.jpg
    output
    ok image.compress earth.jpg -> small.jpg  6.2MB -> 475KB (-93%)  0.74s

  6. Created [small.jpg](small.jpg) at 475 KB, preserving the original 3000 × 3002 dimensions.

Output

small.jpg 475.0 KB · 3000x3002
small.jpg

CodexWith deft, skill as AGENTS.mdPassed2026-11-05

Time
17s
New tokens
10.4k
Total input
77.2k
Output tokens
0.4k
Commands
4
Failed
0

Trace

  1. I’ll inspect the image dimensions and use `deft` to compress it while preserving them.

  2. deft image --help
    output
    deft image - commands (input -> output)
  info      image -> report  Format, dimensions, EXIF orientation, GPS
  compress  image -> image   Smaller file: --quality, --target-size 200KB
  convert   image -> image   Change format: --to png|jpg|webp|avif|gif|tiff|bmp|ico
  crop      image -> image   Cut a region: --box x,y,w,h or --aspect 16:9
  flip      image -> image   Mirror: --direction horizontal|vertical
  resize    image -> image   Scale: --size 800x, 1920x1080, 50%
  rotate    image -> image   Turn clockwise: --angle 90 (EXIF is applied first)
  strip     image -> image   Remove EXIF, GPS and text metadata
  to-pdf    image... -> pdf  One page per image, in the given order
More: deft image <command> --help
  3. deft image info earth.jpg
    output
    ok image.info earth.jpg  3000x3002
has_gps=false has_metadata=true height=3002 orientation=1 width=3000
  4. deft image compress --help
    output
    deft image compress - Smaller file: --quality, --target-size 200KB

Usage: deft image compress <image>... [-o <image|dir>] [options]
In: image (each handled separately)   Out: image (default <name>.compressed.<ext>)
JPEG re-encodes. PNG is optimised losslessly (target size does not apply).

Options:
  --quality <n>                JPEG quality (default 75)
  --target-size <bytes>        Lower JPEG quality until output <= this size
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft image compress photo-1.jpg -o small.jpg
  deft image compress photo-2.jpg --target-size 100KB -o tiny.jpg

Result fields: bytes_before, bytes_after, ratio, quality
Errors: TARGET_UNREACHABLE
  5. deft image compress earth.jpg --target-size 490KB -o small.jpg && deft image info small.jpg
    output
    ok image.compress earth.jpg -> small.jpg  6.2MB -> 489KB (-92%)  0.64s
ok image.info small.jpg  3000x3002
has_gps=false has_metadata=false height=3002 orientation=1 width=3000

  6. Created [small.jpg](small.jpg). It’s 489 KB and keeps the original 3000 × 3002 dimensions.

Output

Its files were not kept in this run. The last line of the trace is its own report.

Claude Opus 5.5Without deftPassed2026-11-07

Time
24s
New tokens
10.7k
Total input
73.2k
Output tokens
1.1k
Commands
0
Failed
0

Trace

    Output

    small.jpg 469.7 KB · 3000x3002
    small.jpg

    Claude Opus 5.5With deft, skill installedPassedRead the skillUsed deft2026-11-07

    Time
    13s
    New tokens
    11.1k
    Total input
    76.3k
    Output tokens
    0.8k
    Commands
    0
    Failed
    0

    Trace

      Output

      .claude/skills/deft/SKILL.md 2.1 KB
      ---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; read QR codes

How to use it:
1. Run `deft <group>` to list commands, or `deft find "<what you want>"` to search. If it says `no command does this`, use another tool.
2. Run `deft <group> <command> --help` for options and examples.
3. `deft convert <in> -o <out.ext>` converts between formats by extension.
4. Results are one line starting with `ok`, `partial` or `error`; add `--json` to parse them. Errors include a `hint:` with the fix.

Inputs are never overwritten; pass `--force` or `--in-place` to allow it. Globs and directories work as inputs; several inputs run in parallel.

If `deft` is not installed, ask the user, then follow https://github.com/firstprayer/deft/blob/main/docs/INSTALL.md
      small.jpg 459.8 KB · 3000x3002
      small.jpg

      Claude CodeWithout deftNot run yet

      Claude CodeWith deftNot run yet