Sizing Images

[rpcrowe]

I want to post images on a website that only allows images up to 10MB to be posted... How can I ensure that I post the very best quality image.

As an example...



This image was shot using my Sony A6400. As it is now the dimensions are as shown in this snip from Photoshop.

Oh yes, I am working with the latest incarnation of Photoshop CC...

By the way... the ugly green skin tones are a result of the Snip It copy - the flesh tones in the original look better...

[Manfred M]

10MP is quite a large image as most modern computer displays are around 2MP (1920 x 1080 is quite a common format), so there is really no issue. Even the 4K displays are running around 8MB, so again, no issue.

Downsize to be less than 10MP and you should be fine.

[xpatUSA]

I want to post images on a website that only allows images up to 10MB to be posted... How can I ensure that I post the very best quality image.

Assuming that you will be posting a JPEG, Richard, I recommend that you use maximum chroma sub-sampling, known as 4:2:0 also known as 'basic'. But use the least compression, sometimes known as 100% quality. Then, if your image file is still over 10MB, reduce the quality until it ain't.

Some will say that 4:2:0 is not the "the very best quality", quoting 4:4:4 instead. But then you might have to apply more compression to get below 10MB which means more compression artifacts.

I assume that your editor can separate sub-sampling and compression. Even FastStone Viewer can do that ...

Of course, as already mentioned, down-sampling to '2K' gets you onto most people's monitors and that could be the way to go, provided that you down-sample correctly in accordance with CiC's tutorials.

[pschlute]

Richard, if the website does not specify a resolution min/max in pixel size, then follow the advice above and select something appropriate.

The purist in me always prefers that the website software does not perform any downsizing on my image so I will usually post an image that I have downsized myself. My own screen is 1440 pixels tall so I would not usually post an image larger than that, and in most cases would post a smaller one to allow for what most people will be view at.

Downsizing an image using the dialogue box you show will reduce the file size considerably. Further, when you choose to save the image you can select the quality if you need to reduce it further. The handy little slider tells you the file size you will be creating.

Even with a 2158*1440 pixel image at a high quality setting I rarely go above 2 MB file size

[xpatUSA]

I want to post images on a website that only allows images up to 10MB to be posted... How can I ensure that I post the very best quality image.

As an example...

Richard, did you mean that the limit really is 10MB, i.e. not 10MP?

Reason I ask is that a file size in MB does not necessarily represent image quality; and also that Manfred changed 10MB to 10MP for some reason.

[Manfred M]

Richard, did you mean that the limit really is 10MB, i.e. not 10MP?

Reason I ask is that a file size in MB does not necessarily represent image quality; and also that Manfred changed 10MB to 10MP for some reason.

A number of organizations and sites that I deal with on a regular basis have file size restrictions on them and they usually have either a maximum file dimension, files size or both and always specify JPEG format files and often at a specific PPT setting.

I shoot raw + JPEG virtually all the time and use the "basic" compression setting on my camera with its 36MP sensor. I see no images that end up being larger than 10MB and if fact they tend to fluctuation in the 5MB to 10 MB range. When I post the occasional SOOC JPEG here at CiC I get no comments on image quality issues.

Ted - I realize that there is no predictable correlation between file size and image size when it comes to lossy compression and perhaps I should have been a little more clear by adding something along the lines of "a 10MB file is unlikely to give you even a 10 MP image. A 10 MP image will have to be downsampled to be displayed on any current computer screen".; something I won't be able to say when 8K screens become common place.

[xpatUSA]

Originally Posted by xpatUSA Richard, did you mean that the limit really is 10MB, i.e. not 10MP?

A number of organizations and sites that I deal with on a regular basis have file size restrictions on them and they usually have either a maximum file dimension, files size or both and always specify JPEG format files and often at a specific PPT setting.

I shoot raw + JPEG virtually all the time and use the "basic" compression setting on my camera with its 36MP sensor. I see no images that end up being larger than 10MB and if fact they tend to fluctuation in the 5MB to 10 MB range. When I post the occasional SOOC JPEG here at CiC I get no comments on image quality issues.

Ted - I realize that there is no predictable correlation between file size and image size when it comes to lossy compression and perhaps I should have been a little more clear by adding something along the lines of "a 10MB file is unlikely to give you even a 10 MP image. A 10 MP image will have to be downsampled to be displayed on any current computer screen".; something I won't be able to say when 8K screens become common place.

Thanks for the clarification, Manfred. I guess Richard is busy.

[pschlute]

Thanks for the clarification, Manfred. I guess Richard is busy.

He is still entertaining his model in the green room