Simple image size question

[anaa122]

Hello, I am new to photoshop and am completing a project. This project asks me to upload an image of my choice, but to make sure the file size is smaller than 2 mb. Is M and mb the same thing in photoshop? No matter how I adjust the w & l, the values under image size I see go from G, M, and K. What can i enter to make my file size 2mb? Also, I've already completed an image for this project, with the size as 3.72M, again needing to be 2mb or smaller. Is 3.72 an appropriate size? If not, am I able to change the image size on an image already finished, and will it distort my photo in any way? I am very new to photoshop so I apologize in advance! Thanks for your help.

[Derek Cross]

I think that M might reprint MB. By the way, you Open an image (not Upload it) in this context. The suitability of the size on an image depends on its use – you need a large image for printing and a  small one for the web etc. Best to produce a large image image and save copies for other use, so you're flexible. You can change the size in Image > Image Size.

Don't worry about asking questions on this friendly forum.

[Per Berntsen]

G means gigabytes (GB), M means megabytes (MB) and K means kilobytes (KB).

One GB equals 1024 MB, and one MB equals 1024 KB.

There is no field where you can enter the desired file size - it will, as you have found out, change when you change the dimensions.

You should also be aware that digital images don't have inherent physical dimensions, they only have pixel dimensions. If you divide pixel dimensions with PPI (resolution), you get physical (printed) dimensions in inches.

Photoshop does the math for you, and displays the physical dimensions.

You may find these articles helpful:

What is a digital image?

File formats

[Abambo]

I have the impression that you are a veteran like me, still noting a kilobyte as 1024 bytes. At some stage in time and quite unnoticed from me and Microsoft, some people decided it was commercially more interesting to set the kb to 1000 bytes. If you go up to the Gb and Tb that will make a packet.

See this for more information on the confusion: Gigabyte - Wikipedia

Now to the essence of the problem:

When someone asks you to upload a file of less then 2mb size you may simply use the Save As menu and save your data as JPEG. By modifying the quality slider, you get the file size under 2mb. Any file size for a digitial image taken by a modern camera (or composed in Photoshop of a similar size of 20-40mega pixels) can be saved with acceptable quality (i.e. you do not see artifacts at a first or even second look) at around 2mb. That’s normally my target size to hand over pictures to my clients.

As Test Screen Name​ points out, it is contraproductive to open a JPEG file and to save again as a JPEG file, open that saved JPEG file and save again as JPEG. JPEG introduces artifacts and they accumulate with each generation. If at the first generation you will need an expert eye to see the artifacts, you can be sure that at the 10th generation even the untrained eye will see the difference. Therefor you should always keep the original Photoshop/TIFF/RAW file with you. If you get a JPEG file, open it with Photoshop, do your work and save it as a TIFF or Photoshop file (both compress lossless, compared to JPEG compression and in addition can keep layers).

At last: You may ask here any question you may have in relation with Photoshop and highly qualified users will try to answer at their best knowledge, even if it is the most easiest beginners question. We all started once with Photoshop and at least with me, the learning curve was quite difficult without de fora.

[Per Berntsen]

Abambo  wrote

I have the impression that you are a veteran like me, still noting a kilobyte as 1024 bytes. At some stage in time and quite unnoticed from me and Microsoft, some people decided it was commercially more interesting to set the kb to 1000 bytes. If you go up to the Gb and Tb that will make a packet.

Exactly, my C: drive is supposed to have a capacity of 256 gb, but in reality it's 238 gb.

255 953 203 200 bytes equals 238 gb.

[Abambo]

https://forums.adobe.com/people/Per+Berntsen  wrote

Exactly, my C: drive is supposed to have a capacity of 256 gb, but in reality it's 238 gb.

255 953 203 200 bytes equals 238 gb.

256 or 250 Gb? While having those odd decimal numbers, capacities are normally ​not​ powers of two.

[Per Berntsen]

Not quite sure what you mean, but the drive was marketed with a capacity of 256 gb.

[Abambo]

2^8=256! 250 is a decimal number. Strange that they label your drive as 256Gb...

[Per Berntsen]

I think they just rounded 255 953 203 200 up to 256 000 000 000, and decided to call that 256 gb.

Of course, highly misleading, 7% less space than advertised.

[Abambo]

https://forums.adobe.com/people/Per+Berntsen  wrote

Of course, highly misleading, 7% less space than advertised.

It's called: marketing! Like the big bottles or containers with big filler space...

But 256 is especially intelligent, as people with background knowledge will assume 2^8 Gb and not 256x10^6 bytes .

[Test Screen Name]

Bear in mind you need to look at the size ON DISK. In Windows Explorer or Finder. NOT IN PHOTOSHOP where it shows you a bunch of different things, none of which are size on disk. You have to save it, check it, save again, until happy. DON'T KEEP OPENING AND SAVING A JPEG, horrible things will happen.

[Nancy OShea]

Find out what file type, height, width and resolution you need to submit.

Exporting your image to JPG should greatly reduce file size.  If it doesn't, you can move the quality slider down and/or make the Image Size width & height smaller.