Image hosting procedures: the short story

[emkraak]

What is the actual size of pictures on this board? I did my best to optimize for 1024 but have a strong feeling the board software still resizes with some loss of sharpness. I'd prefer optimizing for actual size... tnx.

[rjlittlefield]

What is the actual size of pictures on this board? I did my best to optimize for 1024 but have a strong feeling the board software still resizes with some loss of sharpness. I'd prefer optimizing for actual size... tnx.

As far as I know, the forum software does not resize or resample uploaded images. It simply serves back exactly what was uploaded.

I just now checked, and sure enough my JPEG spiderweb from viewtopic.php?p=304306#p304306 is bitwise identical to what I uploaded.

Once upon a time (Jul 09, 2020), right after I installed the current forum software, it did resize & resample images. I considered that completely unacceptable so I spent quite some time to track down and turn that off.

If your images look different in your browser when viewing the forum, compared to how they looked in your photo program before you uploaded them, then I suspect that your browser is doing some mischief to them.

That certainly happens on my systems because my displays are set to greater than 100% and the browser honors that by upsizing. In contrast, my photo editing programs either show the images at their natural size (without upsizing), OR they use their own upsizing algorithm which is different from the browser's.

I suggest to run some careful tests on your own system. One simple test is to open a new page in your browser, and display your image by dragging the file into that new browser page. I'll bet it then looks the same in that new page as it did from the forum, except of course for the forum's gray surround.

If you do find that an image file is getting altered by uploading and getting served back, then I will be very interested to learn the gory details of what software and process you're using.

--Rik

[emkraak]

Just did some quicky tests. Have 3 browsers ready here: Firefox, Edge and Chrome. All resize their own way which means the showed measurements in pixels are not hard but percentual or otherwise interpreted. When I open a picture in a new window/page in FF and Edge it shows true measurements, Chrome is hopeless though as usual.
You are correct in that the file is not altered, so this must be in the HTML- or stylesheet coding somewhere (then, not browser because the FF and Edge open pictures correctly while Chrome does not).
I also see the website problem... when all is cascaded percentually, an absolute picture measurement can disrupt all (like: window not fitting on too small screens so rulers appear) unless the px measurement is overruled. Picture size as shown is ruled by width, not height, which can be made visible by changing window size.
Edit: Even when picture size (width/heigth in px) is given in for instance <dl class="file"><dt class="attach-image"> it can be easily overruled in HTML/CSS somewhere.

Possibly this shows only to me if all other users have bigger screens... mine is 1280x1024px. I see dividers 20/80% in source code - looks like that exactly fits a 1024px picture but does not because of margins/paddings nested somewhere in HTML or CSS. If it's just me... so be it and now I know I have to open pictures in new window to view correctly. On the other hand, if the actual pixelmeasurement does show in big(ger) screens there should be increasingly more white as the used window is big(ger) - obviously I cannot test that. Anyhow the problem is located and I should not over-sharpen to look correct on my browser screen.