Quick start
- Choose Import in the upper-left corner and select photos, files, or clipboard content.
- Choose a publishing recipe and clarity level. Suggested ratios never change composition automatically.
- Hold the preview to see the original, or drag the comparison divider.
- Choose Save Copies to add results to Photos, or use the system share sheet.
Importing
Why can't I browse the entire photo library?
SuTu uses Apple's system photo picker and receives only the items you select. Import again to add more, up to 20 per batch.
Why did a Files import appear to do nothing?
Make sure the file has downloaded completely and is not password-protected or damaged. For cloud files, open the item once in Files before importing.
Why does Paste say there is no usable image?
The clipboard is read only after you choose the paste action. Copy an image first; text, links, or unsupported content leave the current queue unchanged.
Why do very large photos take longer?
Large photos use a lightweight preview, then return to original data during export. Batch work is sequential to control memory. Files over 50 MP or 50 MB are rejected.
Quality and recipes
Can SuTu guarantee that a platform will not compress my image?
No. Platforms may vary processing by account, network, client version, and content. SuTu provides conservative engineering guidance, not official settings or an absolute lossless guarantee.
Why add sharpening after resizing?
Downsampling softens edges. SuTu applies limited pre-compensation from the selected recipe and caps final sharpening based on output size and resize amount. You can reduce or disable it.
Will a suggested aspect ratio crop automatically?
No. Ratios are composition starting points. A crop applies only after you open the crop tool and confirm it.
Do all photos in a batch receive the same crop?
No. The batch shares the recipe and enhancement values, while crop, rotation, and flips remain independent for every photo.
Why is WeChat Moments 2K marked experimental?
WeChat does not publish one fixed rule for every client and scenario. The recipe keeps more pixels, but later processing may still vary. Test with a non-critical image first.
Saving and sharing
Why can't I save to Photos?
Open Settings → Privacy & Security → Photos → SuTu and allow adding photos. You can use Files or the share sheet without granting this permission.
Where are saved photos?
Successful saves appear in Recents in the system Photos app. SuTu requests add-only access and does not create or read a dedicated album.
Can I stop a batch export?
Yes. Saved items are not written twice. Remaining items become Continue N items, and failed items can be retried selectively.
Formats and limits
- Imports include JPEG, PNG, HEIF/HEIC, WebP, TIFF, and the first frame of GIF files.
- Animated GIF output is not preserved in the current version.
- Exports support JPEG, PNG, and HEIC.
- A batch contains up to 20 items; each file is limited to 50 MP and 50 MB.
- General sharing output uses SDR sRGB. Transparency is composited over white for JPEG and HEIC.
Privacy and local data
Photo processing never passes through a SuTu server. Preferences, small history thumbnails, and preview cache stay inside the app sandbox and can be cleared in Settings and History.
Contact support
Include the app version, iOS or iPadOS version, device model, steps, and the message you saw. Avoid attaching private original photos unless they are genuinely necessary.