Evals / image / Background and transparency

Flatten transparency

Convert dice.png to dice.jpg with a white background where it is transparent.

The task

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

deft image convert dice.png -o dice.jpg

Input

dice.png 219.3 KB · 800x600

Reference output

dice.jpg 41.6 KB · 800x600

How a result is judged (2 checks)

image: file = "dice.jpg", format = "JPEG", width = 800, has_alpha = false
script: run = "corner_is_white.py"

Runs

CodexWithout deftPassed2026-11-07

Time: 11s
New tokens: 3.3k
Total input: 40.1k
Output tokens: 0.3k
Commands: 2
Failed: 0

Trace

I’ll check the image and convert it in the current directory, compositing any transparent pixels onto white.
rg --files -g 'dice.png' -g 'AGENTS.md'
output
```
dice.png
```
sips -s format jpeg -s formatOptions 90 dice.png --out dice.jpg
output
```
dice.png
  dice.jpg
```
Converted [dice.png](<dice.png>) to [dice.jpg](<dice.jpg>). JPEG transparency was composited onto white.

Output

dice.jpg 49.9 KB · 800x600

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

Time: 13s
New tokens: 4.2k
Total input: 56.2k
Output tokens: 0.3k
Commands: 3
Failed: 0

Trace

I’ll check the image conversion instructions, then convert `dice.png` to `dice.jpg` in the current directory with transparent areas filled white.

cat .agents/skills/deft/SKILL.md

output

---
name: deft
description: "Use deft instead of writing a script for file jobs: PDF merge/split/compress/watermark, image resize/convert/compress, video and audio trim/convert/compress, spreadsheets, Markdown to PDF/HTML, and YouTube downloads and subtitles."
---

# 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, filters, montage, OCR
- `video`: Trim, crop, speed, convert, compress, GIF, frames (ffmpeg)
- `audio`: Convert, trim, merge, fade, speed, tag, normalize (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline, PDF handout
- `data`: JSON/YAML/TOML/XML: convert, query with jq syntax, merge, diff
- `sheet`: Excel/CSV/ODS tables: filter, sort, join, pivot, convert
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word, PDF; screenshots
- `epub`: E-books: info, to text, Markdown and PDF
- `email`: EML files: headers, text, attachments
- `contact`: VCF address books: to and from CSV
- `calendar`: ICS calendars: to and from CSV
- `gps`: GPX and KML tracks: convert, distance and time
- `youtube`: Info, download, audio, subtitles, thumbnail (yt-dlp)
- `file`: Any file: hash, duplicates, batch rename, base64, encoding
- `qr`: Cre
… 728 more characters

deft image convert --help

output

deft image convert - Change format: --to png|jpg|webp|avif|gif|tiff|bmp|ico
Same as: deft convert

Usage: deft image convert <image>... [-o <image|dir>] [options]
In: image (each handled separately)   Out: image (default <name>.<ext>)
WebP output is lossless. Transparent areas become --background in JPEG.

Options:
  --to <png|jpg|webp|avif|gif|tiff|bmp|ico>
      Target format (or give -o name.ext)
  --quality <n>                Quality for JPEG and AVIF (default 85)
  --background <color>         Fill for transparent areas in JPEG (default white)
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft image convert photo-1.jpg --to png -o photo.png
  deft image convert *.jpg --to webp -o web/

Result fields: width, height

deft image convert dice.png -o dice.jpg --background white
output
```
ok image.convert dice.png -> dice.jpg  800x600  0.01s
```
Converted `dice.png` to [dice.jpg](dice.jpg) with a white background for transparent areas.

Output

dice.jpg 41.6 KB · 800x600

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

Time: 7s
New tokens: 4.9k
Total input: 45.5k
Output tokens: 0.2k
Commands: 2
Failed: 0

Trace

I’ll check the available `deft` image conversion options, then convert the file in the current directory with transparent areas composited onto white.

deft image convert --help

output

deft image convert - Change format: --to png|jpg|webp|avif|gif|tiff|bmp|ico
Same as: deft convert

Usage: deft image convert <image>... [-o <image|dir>] [options]
In: image (each handled separately)   Out: image (default <name>.<ext>)
WebP output is lossless. Transparent areas become --background in JPEG.

Options:
  --to <png|jpg|webp|avif|gif|tiff|bmp|ico>
      Target format (or give -o name.ext)
  --quality <n>                Quality for JPEG and AVIF (default 85)
  --background <color>         Fill for transparent areas in JPEG (default white)
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft image convert photo-1.jpg --to png -o photo.png
  deft image convert *.jpg --to webp -o web/

Result fields: width, height

deft image convert dice.png --to jpg --background white -o dice.jpg
output
```
ok image.convert dice.png -> dice.jpg  800x600  0.01s
```
Converted `dice.png` to `dice.jpg` in the current directory with transparent areas filled white.

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: 10s
New tokens: 8.8k
Total input: 42.0k
Output tokens: 0.5k
Commands: 0
Failed: 0

Trace

Output

dice.jpg 49.6 KB · 800x600

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

Time: 9s
New tokens: 9.8k
Total input: 59.4k
Output tokens: 0.4k
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

dice.jpg 41.6 KB · 800x600

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