Shrink oversized covers without enlarging small ones¶
Reduce the longer side of large embedded images to at most 600 pixels while
keeping their proportions. This recipe changes the pictures inside selected
audio files; it leaves a separate folder.jpg untouched.
Choose the scope before applying¶
Adjust Cover as an action affects all embedded pictures in each selected file, including back covers and booklet images. If only selected front pictures should change, use Manage covers…, select those rows and choose Adjust… there instead; its changes wait for that dialog's OK.
Keep original copies before shrinking or converting images. Resampling can remove detail, and a small source cannot regain detail by being enlarged. A player that requires a square or JPEG image needs a different explicit choice, not an assumption that every resize produces one.
Apply a maximum-size proportional resize¶
- Save or discard pending edits and select a few copied practice files.
- Choose Actions → Actions (Quick)…, then Adjust Cover.
- Use these settings and inspect their scope once more.
- Choose Apply action and inspect dimensions and file errors afterward.
| Setting | Value |
|---|---|
| Image format | Original |
| Quality | High (90 for JPEG) |
| Resize cover | On |
| Size in pixels | 600 |
| Size policy | Maximum size |
| Scaling | Scale proportionally |
Quality applies when encoding JPEG. It does not select dimensions or control PNG compression. With Original format, an already small image keeps its format and bytes when no resize is needed.
| Original width | Original height | Result width | Result height |
|---|---|---|---|
1600 |
1000 |
600 |
375 |
800 |
1200 |
400 |
600 |
1200 |
1200 |
600 |
600 |
400 |
400 |
400 |
400 |
For a 1600 × 1000 picture, 600/1600 is the scale, so the other side becomes 1000 × 600/1600 = 375. The longer side controls the maximum. The 400 × 400 picture is already within it and is not enlarged.
Picture type and description remain associated with adjusted artwork. An action can resize several pictures in one file; inspect all of them rather than only the image currently displayed first.
Distinguish maximum, minimum and square policies¶
These examples all use Size in pixels 600, but change the other controls:
| Original width | Original height | Size policy | Scaling | Result width | Result height |
|---|---|---|---|---|---|
1200 |
800 |
Maximum size | Scale proportionally | 600 |
400 |
1200 |
800 |
Minimum size | Scale proportionally | 900 |
600 |
1200 |
800 |
Maximum size | Scale to square | 600 |
600 |
1200 |
800 |
Maximum size | Crop to square | 600 |
600 |
400 |
200 |
Maximum size | Crop to square | 400 |
200 |
400 |
200 |
Minimum size | Crop to square | 600 |
600 |
Minimum size matches the shorter side and can enlarge an image. Scale to square stretches it; Crop to square keeps proportions while discarding excess around the center. Under Maximum size, an already-small image stays unchanged even when a square scaling choice is selected. Check the result instead of using that combination to force every small cover square.
Choose encoding deliberately¶
Original keeps a supported writable original format. Select JPEG or PNG when a new encoding is intended or the original format cannot be written. JPEG does not preserve transparency; inspect its appearance before replacing transparent originals. PNG can preserve it. Changing a filename extension alone does not convert image bytes.
A JPEG whose format and dimensions remain the same is left byte-for-byte unchanged, even if Quality was changed. Quality alone is therefore not a “recompress all JPEGs” command. When conversion or resizing occurs, file size still depends on content, dimensions and encoding; a quality number is not a guaranteed byte budget.
Save timing and recovery¶
The action writes when run. Save groups stores a reusable setup without running it; applying its checked group does the work. In Manage covers…, Adjust stages replacement images and OK commits the plan. A direct cover window Adjust cover… has its own immediate operation.
Inspect errors and saved artwork on the intended player. A successful core resize is not proof that a particular device accepts that size, format or picture role. Use Edit → Undo … for recorded writes in the current desktop session and keep original images/audio for recovery beyond it.