How can I delete an attached image from a post?

Hi John

I want to delete the image attached to this post of mine and replace it
with a smaller one. It's a bit too big for my liking.
https://forum.nodebox.net/t/5252647822/teaser-for-a-little-tutorial-which-will-follow

But apparently a user can't do this in their one post ?

Thank you in advance
gottfried

Gottfried,

I have admin privileges, but am still fairly limited in what I can do. I looked around the forum site; I can edit the text of your message but could find no way of editing files once they've been uploaded or changing which files are attached to a message.

The one thing I can do is delete the message entirely. You could then repost it with a smaller image. You would lose any replies to the original message though and would have to retype the text. I can do that if you want.

I don't see why you would want to make the image any smaller, though. It's pretty tiny as is, both in terms of file size and dimensions. Looks great by the way.

Let me know.

John

John

Thanks, if it's OK on your monitor, then I'll leave it as it is.
I suspect it's a resolution/monitor problem.

I use a 32-inch monitor and a resolution of 1920 x 1080.
That's probably why images appear larger to me
than they are to other viewers.

Thanks again
gottfried

Here us how it looks on my iPhone...

John
:)

I usually keep the image resolution in the range
of 500 or 600 pixels.

What pixel resolution would be fine in your opinion?
In my opinion it doesn't have to be that big but logically
not too small either.

Thanks
gottfried

Gottfried,

Choosing a resolution can be surprisingly complex. I am still learning the best rules of thumb.

The first thing to consider is whether you are making your image for screen or for print.

In general print images will require higher resolutions, depending on where the printout will appear - e.g. in a magazine or on a billboard. For a magazine or a framed photograph you will usually want at least 300 dots per inch, so an 8 x 10 image would require 2400 x 3000. If it's going to hang on the walls of a museum - where people can look at it closely - at, say, 30 x 40, you would need at least 9000 x 12000, maybe more if you are printing at 2400 dpi. (Using American units, but you get the idea.)

For a billboard, oddly enough, you can get away with lower resolution because people won't be able to get very close to it. In most case just 3 or 4 thousand pixels on a side will look fine even for images measured in meters.

For screen images something like 72 or 96 dpi will usually be fine. Again, it depends on how big you expect the screen to be and how close people's eyeballs will be to that screen. Even a fairly big laptop screen will only be around 1000 pixels tall. So, like you, I find that dimensions of around 600 pixels will work find for images which are just going to appear on a web page or something and will not be zoomed into or scrolled.

BUT, if your image has a lot of fine detail (e.g. text) you may want to at least double the expected display size to reduce visible antialiasing. Your image was simple geometic shapes without text or much in the way of curves, so keeping it under 600 on a side was fine.

For animations you can get by with fewer pixels because they are zipping by too fast to be seen in detail. I used to make my animations at 600 x 600, and they looked pretty good at that size when viewed on an iPad or even when projected on a wall. But Instagram and many current display screens are optimized for at least 1080 by 1920, so that's what I use now. They look great even on large screen TVs.

Yet another factor for screen display is the layout: landscape or portrait, for both the image and the screen. Especially on web pages, the display code will size the image differently depending on device proportions. For a phone, which is normally held in a portrait orientation, or a web page, where there is a fixed width but a potentially infinite height (with scrolling) the code will first stretch the width to fill the available space and then size the height to match the image's proportion. In situations where both height and width are fixed and height may be in shorter supply, like dialog boxes, the code will stretch height first and then set width based on the image.

In your case, this particular image happened to be taller than it was wide and the width, 416 pixels, happened to be just under the maximum width for display in the forum web page, so no shrinking was required. It left the width as it was and so also left the height as it was, which, at 554 pixels is just a little taller than many images on the forum - almost the entire available height without scrolling on my iPad. If your image had been landscape instead of portrait, it would have reduced the width a bit and the height, already less, would have been reduced by the same amount, resulting in a image which would appear noticeably smaller on the page.

SO, bottom line: it's complicated. For display on a Nodebox forum web page, on a phone, tablet, or laptop screen, for an image that does not require zooming to see fine detail, the image will need to end up under about 450 pixels wide. If you don't want people to have to scroll to see the whole height, you'll want to keep that under about 600 pixels (or 4/3 your width).

So your image was just under the maximum size for that particular viewing situation given its proportions. If your image had been twice as tall as it was wide, you would have probably needed to shrink it down to about 300 pixels wide to keep the height under 600. But at its current proportions you could have doubled the resolution to 832 x 1108 and the display would have probably looked about the same (since the web page would divide both dimensions in half).

Sorry for such a long answer.

John

No need to apologize for the long answer. Find it allways
interesting to hear what others say and i am able to pick the
Information i need.

Other Nodebox Forum readers may also be thankful for
the information.

Will keep in account what you wrote when posting

Thank you
gottfried

Gottfried,

After a good night's sleep I think I should have edited my last comment before submitting it. It's a rambling note that could be misleading. I certainly wouldn't want anyone consulting it as an official guideline about preferred image sizes for comment attachments.

Although I suggest 450 pixels for maximum width for simple images with no need for zooming, I should have also mentioned that I routinely attach full screen screenshots taken from my Mac Pro that weigh in at 3456 x 2234! Yet they occupy less screen space than your small image.

I don't bother to compress those screenshots out of pure laziness. And they display at a convenient size on both my laptop and iPad. But in any case I would want them somewhat high res because, unlike your image, I do want people to be able to zoom in in case they want to try read the node labels on the right.

These pixel dimensions are SO confusing! For example, consider this screenshot of your image and a screenshot of your image side by side (attached). Your image is 416 x 554. The screenshot of it, which looks identical, is twice as big: 834 x 1105. This happens because Apple's Retina display automatically doubles the pixels in order to make small text easier to read (because the physical pixels on their high-res screens are now so tiny).

The side by side comparison image I attached is 2948 x 1316, yet, because it is so much wider than it is tall, it will take up far less physical screen space on my laptop's browser webpage than your small portrait image did.

So what can we conclude from all this? I would recommend not worrying too much about the pixel dimensions of images you attach to forum posts. If it looks OK on your device before you upload it, it will probably be fine when people view it on the forum.

John

Thanks for the Info, always interesting.

...So what can we conclude from all this? I would recommend not worrying too much about the pixel dimensions of images you attach to forum posts...
:)

This is, no joke, a very practical solution.

Thanks
gottfried