How to resize photos? [solved]

Hello,

A while back I learned how to take good quality photos, and now I have a new problem; sometimes the photos are too good, too high resolution, and therefore too large to upload to Numista coin pages without the error screen.

So what can I use to lower the resolution of a photo, and what is the maximum size of a file that can be uploaded to a coin page? I want to upload these pictures of my AU 1896 A 1 Centime to replace the ones in the catalogue now, but they're both too big at the moment (obverse pic is approx. 1979x1878 pixels):

I've been using GIMP for resizing images before converting from TIFF to JPG and uploading them. Unfortunately, the new GIMP 2.10 replaced the old sinc/lanczos interpolation method with something called LoHalo, whch is very fuzzy.

Do you use a Windows computer?
MS Paint has a re-size tool that works well.

Quote: "Mr. Midnight"​Do you use a Windows computer?
​MS Paint has a re-size tool that works well.

​ Agreed - here is the current picture, size 1991x1878, then just overtype with any size required ...

.
such as change (horizontal) 1991 pixels to say 1500 then vertical is
automatically adjusted from 1878 to 1414 pixels.

Quote: "Mr. Midnight"​Do you use a Windows computer?
​MS Paint has a re-size tool that works well.

​Unfortunately, no, I'm on Mac.

Most of the tutorials on cropping photos here seem to be Windows-oriented....

Marked as solved because it turns out the program I was using (Paintbrush) has a size function too.
Now the photos are pending approval, thank you!

I've added dozens of high quality photos to replace bad, grainy ones on many Numista pages recently, mostly in France and the UK, and I'll be adding many more soon.

I'd still like to know what the maximum size a file can be to be uploaded to Numista page, so as to preserve as much resolution as possible.

I can upload 3000x3000, as far as I have seen.

Quote: "SquareRootLolly"​I can upload 3000x3000, as far as I have seen.

​Really?

I tried uploading some images to a coin page that were ~2400 x ~2400, and it resulted in the Error 413 page.

At the moment I'm shrinking my photos to 60%, that seems to work.

I think quality tops resolution ... I'd rather have a knife sharp 1000x1000 picture than a blury 3000x3000.
For example the picture of Ms. Taylor's centime is a bit out of focus and doesn't gain much from high resolution.

I think the limits are: bigger than 8MB or longer upload time than 1 minute.
A picture of a coin most often round (1:1) would need to be around 1670x1670 to reach 8MB (24bit, without extra compression).

Quote: "Idolenz"​I think quality tops resolution ... I'd rather have a knife sharp 1000x1000 picture than a blury 3000x3000.

I thought resolution and quality were interchangeable terms in this context (as in, by decreasing the photo's resolution, quality drops)! Quality, then.

How would I see how big (in MB) my file is? Usually my upload times are between 20-30 seconds. And if the above is correct, then does quality/resolution not actually matter compared to file size?

And as much as I like my psuedo, I must admit Taylor is not actually my surname.

For me the quality of a coin picture is the amount of "useful" information, resolution often plays a part in it but loses importance when reaching higher dimensions and is more a size than a point in quality.


For example this left picture is the original (307 kB), the right picture (182 kB) was altered so that 16 pixel represent 1 pixel of the original. The resolution is the same, but I would certainly say the original picture is the higher quality one.

Also, it depends on what you are watching it be it a desktop display or a tiny but high-resolution smartphone display. Personally, I care more about desktop/laptop issues ... anything more than looking at the catalog or reading the forum is too much of a hassle on a mobile phone.

P.S. No intend on using IRL surnames names anyways.
I would say click on the file or hover above it and somewhere you can read the file information or right click but apple does't have this so I can't tell you where to look but shouldn't be so difficult for such a basic function.

Alright, so if I have this right, it's MB, not pixels x pixels that I need to be looking at if I don't wish to encounter the 413 Request error.

I'll look up how to check file size on Mac soon, thanks for your help @Idolenz!

(Firstly, my apologies for the shrunken pictures. If I increase the size of these screenshots, they will be blurry, so for those who do not know, click to enlarge.)

To look up the size of a picture, I just save it, go to my pictures, click the picture, and read the bottom. I am not sure if that works on non-windows programs, but this is what your reverse is saying (3.92 MB):



With that in mind, I notice your image is a PNG. As far as I am aware, PNG images are not allowed to be uploaded as the main pictures for a coin page. I am not exactly sure what the 413 Request error is, but this is what I get when I try to upload a PNG:



If you go to Paint or probably any image-cropping software (I use PhotoScape), you should be able to turn your PNG image into a JPEG (and I have never come across any errors when uploading a JPEG image on this site). If you change you reverse image to a JPEG, your pictures should also shrink in size (your reverse turns into 1.80 MB):

Quote: "Sulfur"​
​With that in mind, I notice your image is a PNG. As far as I am aware, PNG images are not allowed to be uploaded as the main pictures for a coin page. I am not exactly sure what the 413 Request error is, but this is what I get when I try to upload a PNG:
​
​
​

​

​Thank you very much!

Yes, you are correct about the .png ending. I've since changed it to .jpg (which is what is pending approval as I type), but did not notice a decrease in resolution.

The 413 request error (or whatever it's called exactly) occurs as a screen when you try to upload an image thats too large to a Numista page; it says "request too big" or something like that.

The first of a few requests I made to replace low-quality/resolution photos with better ones of my own:
https://en.numista.com/catalogue/pieces12526.html

Here's the program (Paintbrush) I used to fill in the space around the coin after cropping, and how it looks when viewing image size (in pixels), file size is 2.3 MB, with uploading time of no more than 20 seconds:


On Mac I can convert images from .png to .jpg just by right clicking the file on my desktop and renaming it.

The original image:

Quote: "CassTaylor"​
​​Thank you very much!
​
​Yes, you are correct about the .png ending. I've since changed it to .jpg (which is what is pending approval as I type), but did not notice a decrease in resolution.
​
​The 413 request error (or whatever it's called exactly) occurs as a screen when you try to upload an image thats too large to a Numista page; it says "request too big" or something like that.

​No problem!

JPEG images are of a slightly less resolution, but for most photographed images, the difference is so insignificant that I cannot tell the difference between a JPEG and a PNG just by looking at them. To see an obvious difference, draw a circle in a paint program and save it as a PNG and as a JPEG. If you then take each image and fill the centre with a colour, you can see the difference:



(Left is JPEG; right is PNG.)

PNG completely perseveres all pixels, whereas JPEG has some blending around the edges, making the pixels nearest to the black line not completely white.

But that is just with using two solid colours. Non-computer made images have so many colours already blended together that the differences become pretty unnoticeable.

Excellent article that I discovered
With a few observations:
For dimensions, at 250x250 the photo is not enlarged by clicking '+' on the photo, so the minimum would be 300x300.
The maximum results in my opinion from a compromise between the dimensions and the resolution to arrive at a size which does not penalize either the small computers nor the download times for those more and more numerous who use a telephone in network sometimes restricted or in reduced package. 3 MB per photo (obverse, reverse, edge) to which descriptions must be added seems to me a reasonable limit.

Quote: "Sulfur".../... If you then take each image and fill the centre with a colour, you can see the difference:

​
Small note: we do not add color to the interior, the clipping consists of having a white exterior background



This background example is intentionally bad to point out that the clipping becomes extremely difficult when the shape is not regular or that the shadow is very thick preventing the one who discovers the piece from determining the exact position of the edges.



Excuse my translated English.

I use Gimp V2.8 to crop coin images that I have already squared off using Paint Shop Pro V5. PSP V5 is actually a fairly old program but it works really well. The makers of the PSP software kept improving it to the point where it is almost impossible to use because they made it too complicated.

So I keep using the old PSP V5 as it is very easy to learn and simple to use. Both PSP V5 and GIMP V2.8 can be used to rotate & re-size images as well.

Cheers Mike