Every PNG your tools save is a bottle with the note still inside. Most people never uncork it.
Every PNG your tools save is a bottle with the note still inside. Most people never uncork it.
The settings you lost three weeks ago are probably sitting inside the image file, waiting for you to look.
Three weeks ago you made the best portrait you have ever generated. You remember the night. You do not remember the sampler, the step count, the guidance value, or which of your four look-alike checkpoints was loaded, because you were fifteen renders deep and none of it seemed worth writing down. Now you want to make a series in that style and the recipe is gone.
Except it almost certainly is not gone. It is inside the file. The tools have been quietly filing your paperwork for you this entire time, and this guide is about how to read it back out, and about the handful of everyday actions that shred it without warning.
The Automatic1111 WebUI documentation describes the feature in one line: it "adds information about generation parameters to PNG as a text chunk." A PNG file is built out of labelled blocks of data, and the format has always allowed extra text blocks to ride along with the pixels. A1111 uses one of them to store the parameters that produced the image, which means the prompt and settings travel inside the same file as the picture itself, not in a sidecar file you can misplace.
Because it is a standard part of the PNG format, you do not even need the WebUI to read it. The wiki points to any software that supports viewing PNG chunk info, and names a free browser-based chunk inspector as an example. Drop the file in and the text block is right there, prompt and all, readable in plain text.
ComfyUI's documentation makes a bigger promise. "When you save an output with a built-in save node, ComfyUI can also store the workflow inside the output file." Not a summary of the settings. The workflow itself, the entire node graph that produced the image.
And the recovery step is the best piece of interface design in this whole corner of the hobby: "You can then drag the file back onto the canvas to recover the workflow." That render from three weeks ago is not just a picture of the result. It is a save file. Drag it into ComfyUI and the graph rebuilds itself in front of you, nodes, connections, values and all, ready to run again or to modify.
This changes how you should think about your outputs folder. It is not a gallery. It is a library of executable recipes, each one disguised as its own cover art.
| What you did with the image | Is the recipe still inside? |
|---|---|
| Kept the original PNG your tool saved | Yes. This is the master copy. |
| Exported or re-saved as JPEG | No. JPEG is a different format and does not carry PNG text chunks, so the block gets left behind in the conversion. |
| Took a screenshot of the image | No. A screenshot is a brand new image of your monitor. Nothing from the original file comes with it. |
| Uploaded somewhere that re-encodes images | Assume no. A platform that recompresses your upload is writing a new file, and your text chunk is not part of the pixels it copies. |
| Cropped or edited, then saved from an editor | Depends entirely on the editor and settings. Treat the edited copy as recipe-free and keep the original. |
Notice the pattern. The metadata survives exactly as long as the original file does, byte for byte. Every operation that creates a new file, and most convenient operations do, is a chance for the note to fall out of the bottle. None of these steps warn you, because from the software's point of view nothing important was lost. The picture still looks identical. Only the recipe is gone.
Here is the same fact wearing its other face. If the full prompt rides inside the PNG, then every raw PNG you share is also sharing your full prompt. The exact wording you spent an evening refining, the negative prompt you are quietly proud of, the model name, all of it, readable by anyone who thinks to look, using a free tool in a browser tab.
For most hobbyists that is a feature. Sharing the recipe is half the culture, and plenty of communities expect it. But if you sell prints, run a commission service, or simply do not want your prompt craft walking out the door, you need to know that posting the untouched PNG is publishing your working notes. The fix is the same list as the table above, run deliberately: export a JPEG or a stripped copy for sharing, and keep the original PNG at home. What destroys the metadata by accident will also remove it on purpose.
Put the two halves together and a very lazy, very effective workflow appears. Never delete the original PNGs of anything you might want to revisit, and never rename them into chaos either, because the file itself is the settings sheet. When you want to study your own progress, pull two originals into a chunk viewer and compare the text side by side: same prompt, different sampler, and now you know exactly what that sampler change did, with receipts. When you want to resume an old ComfyUI project, drag the output back in and you are standing exactly where you left off.
People build spreadsheets for this. The spreadsheet already exists, distributed across your output folder, maintained by software that never forgets to fill in a row.
The statement that generation parameters are added "to PNG as a text chunk," and the pointer to reading them with any software that supports viewing PNG chunk info, were read today from the Automatic1111 WebUI features wiki. The statements that a built-in save node "can also store the workflow inside the output file" and that "you can then drag the file back onto the canvas to recover the workflow" were read today from the ComfyUI documentation's workflow page. The observation that JPEG files do not carry PNG text chunks follows from the two being different file formats, and the screenshot and re-encoding rows in the table are reasoning from how those operations work, not tested claims about any specific platform's upload pipeline. No claim is made here about which websites strip metadata and which preserve it, because that varies and was not tested.