Thanks Toni - but I'm quite confused and rather depressed
I CAN see a problem with the rope, yes - but struggle to understand about the wall (but let's not dwell on that)
First is exporting the image using too much jpg compression. The smaller the number selected for output quality, the smaller the image file will be as more and more data is lost in compression. Lose too much data and effects like this become increasingly obvious - this often shows up as banding across skies where the colour changes in steps instead of a smooth gradient. Cure - don't over-compress images on jpg output: I normally use 91 for Flickr where images get exported or 75 for images that don't get resized.
I'm totally lost on this - I haven't come across "jpg compression", or numbers like 91 or 75. Where do these appear and why haven't I see them??
Second exporting with too much sharpening. That can make jaggies more obvious as the software tries to increase the fine contrast between areas that change sharply in tone and shade. Cure - if using Lightroom then output at either low or standard sharpening for screen depending on the nature of the image.
I believe I have been guilty of over-sharpening images (probably still am!) I think I'm overcoming this slowly.
Third allowing Flickr to re-size an image for embedding. Sometimes the resizing algorithms don't favour already slightly over-stressed images, and what looks fine at 1200 X 800 gets really messed up when resized to 900X600 on the fly in a browser. Cure - for uploading to flickr keep image sizes a bit larger (to give more data for smoother resizing) and avoid deliberately embedding the images at smaller resolutions on sites like TP where we'll analyse each others pictures critically. If you want a smaller image to look its best on the web then output it at required resolution and don't allow any further resizing.
Again, I'm a bit lost here, particular the word "embedding" - what exactly is that and when is it applied/used? I shoot in RAW/jpg, although I rarely utilise the RAW images unless the jpg is not satisfactory. Numbers confuse me and I've always taken the view that I need to reduce sizes to save space with saved images.
Looking at a recent photo - RAW image, 6000x4000, 23,414kb; jpg 14,006kb. Obviously I won't want to store saved images that big or space will soon disappear, so, as a rule of thumb (don't know why, just how I've worked), I resize worked jpg to 2000x1333. There is the option in Photoshop Elements to save the image at different levels and I use 9 (high), which, in this case, gave me 1,525kb. At 12 (maximum) it would be 2,893kb. Much more manageable sizes, I would have thought. The former (9) is the image I save at and use on flickr (my photo site!).
I'm not sure how this relates to your work, if at all! Probably not. Am I totally wrong here (if so, which way to go)?
Apologies if this is off-topic, but it's how discussions seem to evolve on forums like this.