HOW TO REDUCE MEMORY USAGE _ PLEASE READ

[BobDarkroom]

PLEASE READ ENTIRELY!

This text explains why attachments use often way too much memory.

First of all I would like to emphasize that I do not want to offend or criticize any creator of artwork (2D, 3D, photo manip …) in what follows! I only want to help avoiding memory shortage.

After all the fuss with a frustrated newbie about forum rules, forum content and memory usage (or should I say electrons usage… ) I decided to have a closer look at image dimensions (i.e. number of pixels) and the associated file sizes. So, I downloaded several artwork from various creators and checked their dimensions in pixels and their file sizes.

Well, I was astonished by the sizes of some 2D and 3D artwork from various well known and much appreciated creators and I came to the conclusion that a considerable amount of memory space could be saved if some basic principles about image sizes were applied to attachments in posts!
Allow me to explain a bit more in detail.

Let me start with monitor limitations. Every computer display has a limited number of pixels it can display in horizontal and vertical directions that you know as the screen resolution. The 3 highest display resolutions (in pixels) currently available are in ascending order:

Full HD : 1920 x 1080
4K : 3840 s 2160
8K : 7680 x 4320

The most common for recent monitors and laptops is the Full HD with a 16:9 aspect ratio between width and height. The 4K and definitely the 8K monitors are still rare and will probably remain that way for some time to go. Just an example: Dell Ultrasharp 32” 8K monitor price is around US$ 4000,-

So, let’s stay with the pixels limits to Full HD as I presume that most visitors of the site have that type of display. For viewers with older and lower resolution monitors that’s OK too as the image will simply be scaled down to fit on their screen by their display driver.

Any image that is more than 1920 pixels wide and/or more than 1080 pixels high will be shrunk by the Full HD display driver to fit on the screen. If its aspect ratio is different from 16:9 the driver simply can’t use all 1920 x 1080 available pixels so there will be black zones either on both sides or on top and bottom.

Assuming full screen display mode can use all available pixels, which is usually not the case because there are menu bars or so on the top and/or bottom of the screen, when displaying images with larger dimension they would be shrunk as following examples for landscape (WxH) orientation (best case):

16:9 pic with 3200 x 1800 pixels will be shrunk to 1920 x 1080 (100% Full HD)
4:3 pic with dimensions 4000 x 3000 pixels will be shrunk to 1440 x 1080
3:2 pic with dimensions 3000 x 2000 pixels will be shrunk to 1620 x 1080

For portrait oriented pics like many drawings, the size reduction will be even worse as the height is now the largest dimension and has to fit into 1080 pixels.
Example : pic with portrait orientation W x H = 3000 x 4000 would be reduced to 810 x 1080.

Now what is the relation with memory usage? Well it’s simple, the larger the pixels count (i.e. dimensions) the larger the file size will be.

An example based on my Canon DSLR camera:
Camera native resolution : 6720 x 4480 pixels
Photo full size after cropping a bit : 6000 x 4000 pixels, JPG file size = 3066KB
Resized copy of 1500 x 1000 pixels file size = 328 KB or 87.8% size reduction!)

That’s an extreme example, but believe me, files of 2MB can be reduced by 50% or more by using a copy with reduced dimensions based on the available pixels count on a full HD screen.

I fully understand that artwork creators use higher to much higher resolutions when creating their work so they can zoom in on details as I do the same with photos that come out of my camera with native dimensions of 6720 pixels x 4480 pixels. For large size prints (e.g. 45cm x 30 cm) is will use the highest possible resolution but for uploading to a website I will make a copy and reduce its size to fall within the Full HD dimensions and for a 3:2 ratio that’s WxH = 1620 x 1080 pixels for landscape orientation but only WxH = 720 x 1080 for portrait orientation.

A 2D drawing example

The wonderful 2D drawings made by various artists here are obviously not drawn at the thumbnail size that appears in their posts but on a much larger scale.
Let’s assume someone draws on an A4 sheet in portrait orientation (210mm wide and 297mm high, 8.3 x 11.7 inches) and when finished scans it full size. When scanning an A4 sheet in portrait orientation at 300 ppi the dimensions of the resulting JPG file will be around W x H = 2500 x 3500 pixels (these are rounded numbers) and the file size will be around 1MB for a grayscale drawing.
Way too much pixels for a Full HD display and way too big file size.
A copy resized to 771 x 1080 so that its height fits the full HD 1080 pixels screen will have a file size of less than 250MB resulting in at least 75% size reduction.

A 3D rendering example

I came across a beautiful 3D rendering and I won’t mention the creator because that’s irrelevant. I’m just using it as an example. I clicked on the thumbnail in the post to open it full size and saved it.
To my surprise the dimensions of this pic were 8000 x 5617 pixels and the file size was 1.49MB.
BTW, surprisingly low for such a big image.
That’s a huge image and its size would allow for printing a poster but is way too big for displaying on a computer screen. Resizing to 1538 x 1080 reduced the file size to 478 KB or 68% reduction.

Conclusions

I plead with all artwork creators (2D, 3D, phot manips …) with or without the use of AI, please check the dimensions of your final creation and if its width exceeds 1920 pixels and/or its height exceeds 1080 pixels, make a copy for posting only and reduce its size so that it falls within the full HD resolution before posting it.

Feel free to comment or ask questions via post or PM.

[yyy02]

...

This text explains why attachments use often way too much memory.
...

Many thanks for this explanation, BobDarkroom!

[doe.1971]

I feel offended! Can't pinpoint it exactly why but my blood is seething.

[wulf]

If the image is in the png format, simply resaving it as a jpg / jpeg will greatly reduce the file size without doing anything else to the image.

[BobDarkroom]

If the image is in the png format, simply resaving it as a jpg / jpeg will greatly reduce the file size without doing anything else to the image.

Wulf, that's correct but most of the big files I was referring to were already in JPG format.

[BobDarkroom]

I feel offended! Can't pinpoint it exactly why but my blood is seething.

I really can't see why you feel offended or were you just being sarcastic?

I didn't mention any names and I only tried to explain that images with dimensions (in pixels) in excess of the maximum number of pixels of a full HD display are taking up unnecessary memory and that they would still be OK for viewing if they were resized to HD pixels limits which would reduce the file size significantly.

Anyway, nothing has changed since I posted this message and Reine Margot doesn't seem to care either as long as the 2MB limit is respected and the number of posts/day is kept low.

So, it looks like it was all a waste of time.

[doe.1971]

I really can't see why you feel offended or were you just being sarcastic?

You must really be new around here. Or might be truth to the saying that Walloons are more serious than the Germans!