explain purpose of the method

README.md

@@ -26,10 +26,16 @@ pipe = StableDiffusionXLPipeline.from_pretrained(model, vae=vae)
 
 For more information, please have a look at [the official demo](https://huggingface.co/spaces/imatag/stable-signature-bzh)
 
-## Decoder Finetuning
+## Purpose
 
 This model was finetuned from the original StableDiffusion-XL autoencoder with the additional objective of including a weak invisible watermark, following the procedure of [StableSignature](https://ai.meta.com/blog/stable-signature-watermarking-generative-ai/). This watermark is detectable by [IMATAG](https://www.imatag.com/)'s demo BZH decoder, available via API.
 
+Compared to other watermarking solutions such as [invisible-watermark](https://github.com/ShieldMnt/invisible-watermark):
+- the watermark is quite robust to many unintentional editing transforms such as cropping, resizing, changing contrast or brightness, and JPEG compression
+- the watermark has zero overhead in terms of computational power
+- the watermark is embedded in the model weights and not as a post-processing of the non-watermarked image
+- the probability of detecting the watermark by chance on non-watermarked images may be computed analytically and limited to a specific threshold
+
 ## Detecting the watermark
 
 For security reasons we cannot release the weights of the detector. Instead, you may check for the presence of a watermark with the [detect_api.py](https://huggingface.co/spaces/imatag/stable-signature-bzh/resolve/main/detect_api.py) script like this: