I have some images (jpg, png) uploaded to aws s3 bucket. I want to extract some informations (lambda is written in golang) from the image (width and height). Is it possible to do this without downloading the image?
You can do a partial download of the object using the range header See this SO answer S3: How to do a partial read / seek without downloading the complete file?
in the AWS go sdk func (Downloader) DownloadWithContext seems like it should provide range feature
Once you have the partial file it may be possible to extract the size information, see this answer What is the header size of png, jpg/jpeg, bmp, gif and other common graphics format?