Image size for client

kitkatdubs · Nov 26, 2015

I am wondering what is typical image size you give to a client. I typically resize my images to around 7MB, but what I notice when I go to the actual jpg on my desktop, it is really like around 1-2MB, not 7MB like I had resized in photoshop. Why is it doing that? Am I missing something here?

KmH · Nov 26, 2015

JPEG is a lossy compressed file type.
Each time a JPEG file is saved the file size is reduced.
Each time a JPEG file is saved it is again compressed and some additional image data is lost (lossy).

1-2 MB is plenty for a retail client file.
Commercial clients are usually given a TIFF file, a file type that is not compressed and is not lossy. TIFF files are often larger than Raw files made of the same scene.

There is image size, the pixels dimensions, and there is image file size which is in Mb or Kb.

The Quality setting in the Photoshop Save (or Save As) dialog box determines how much compression gets done beyond the compression already done in the camera if the photo was made in the camera as a JPEG.

Note too that file size is dependent t on image content. A photo of a section of a painted wall with nothing else on the wall will have a smaller file size that a shot of the same section of wall with a framed photo/painting on it.

If you're making JPEG files in the camera instead of Raw files, be aware that the JPEG file type was designed to be a ready-to-print file type that would not be edited outside the camera.

Photo Editing Tutorials

kitkatdubs · Nov 26, 2015

I am shooting in raw but I upload to iPhoto which converts them to JPEG. In photoshop when I do "Save As" it gives me these options at the end. Which one should I be choosing in order to keep the best quality for the photo?

KmH · Nov 26, 2015

Will the photos be printed, or just looked at electronically?

kitkatdubs · Nov 26, 2015

KmH said:
Will the photos be printed, or just looked at electronically?

Only a few will be printed via tinyprints for a Christmas card. The rest will be used for social media share.

KmH · Nov 26, 2015

Then any file size 100 kb or larger than will be fine.

Vtec44 · Nov 27, 2015

IMHO, the file size is not as relevant when it comes to printing size. You should pay attention to PPI since that will be a more precise way to judge how big a photo can be printed.

KmH · Nov 28, 2015

The ppi (print resolution or pixels per inch) AND the image resolution (pixel dimensions) determine how big a print will be - if the print will be made on an inkjet printer.
Ppi is meaningless for prints made by the chromogenic, light sensitive paper/wet chemical development, print process or by an off-set press printer.
For off-set press printing you would want to be familiar the CMYK color model and lines per inch (lpi).

A 24 MP Nikon DX image sensor has pixel dimensions of 6016 pixels by 4000 pixels, and an aspect ratio of 3:2.
6016 px / 300 ppi = 20.05 inches and 4000 px / 300 ppi = 13 inches
Aspect ratio defines the shape of the image frame. 3:2 is a rectangle whose long side is 1.5 x longer than it's short side (3 / 2 = 1.5).
5:4 is less rectangular than 3:2 and 5:4 is closer to being square.
A square image frame has equal sides and a 1:1 aspect ratio.

Pixel / pixels per inch = inches (Note: the pixel units cancel leaving Inches as the unit of the result.)

But your client wants a print that is smaller than 20 x 13 AND that has a different aspect ratio.
An 8x10 has a 5:4 aspect ratio, and a 5x7 has a 7:5 aspect ratio.
So your client wants a 5:4 aspect ratio 8 x 10 print made from your 3:2 photo and because of the difference in aspect ratio part of the original 3:2 photo isn't included (cut off) on the 5:4 print.

The client doesn't know about print types, print resolution, image resolution or aspect ratio, and why should they?
Those are technical considerations for printing the photographer is supposed to know about and should care of for the client.

So lets go back to that simple math equation above that solves for inches - Pixel / pixels per inch = inches
From that equation, and the use of basic algebra, we can derive 2 more equations. One equation to solve for pixels, and another to solve for pixels per inch.
And here they are:
Inches x ppi = pixels
Pixels / inches = ppi

(Note: a 6016 x 4000 pixel 3:2 aspect ratio photo with no cropping, can print as a 8 x 12 but at 501 ppi instead of the 300 ppi in the example above.
6016 px / 12 inches= 501 ppi)

So the 6016 x 4000 px 3:2 aspect ratio photo has to be cropped to 5:4 for a 8 x 10 print.
Start with the determining what ppi we need to make the short side 8 inches using the pixels / inches = ppi equation
4000 px / 8 inches = 500 ppi.

Now that we have the ppi - 500 ppi - we can calculate how many pixels we need for the long side to be 10 inches long using Inches x ppi = pixels:
10 inches x 500 ppi = 5000 pixels

The last calculation is just subtraction 6016 px - 5000 px - 1016 pixels that need to be cropped off the long side, 508 pixels from each side if we crop each side evenly, to get to 5000 pixels on the long side. Or we can set the pixel dimensions in our Crop tool options dialog and then move the 5000 px wide crop on the original photo to get the framing we want within the 5000 pixels.
Either way we crop we wind up with 5000 px by 4000 px image frame - the same 5:4 aspect ratio of an 8x10.

If we want a 2x bigger 5:4 print - a 16 x 20 - we just halve the ppi from 500 ppi to 250:
4000 px / 250 ppi = 16 inches and 5000 px / 250 ppi = 20 inches.

For a 32 x 40 print we halve the ppi again to 125 ppi :
4000 px / 125 ppi =32 inches and 5000 px / 125 ppi = 40 inches.

Vtec44 · Nov 28, 2015

In short ppi has a more direct relation to printing size in most type of printing, minus a few specialized ones.

kitkatdubs · Nov 30, 2015

I checked the PPI on a lot of my photos in photoshop, and they ALL say 72. Do I need to change that for each photo to 300?

KmH · Dec 1, 2015

No.
The ppi a photo needs to be set to depends on how big it will be printed. Some will need to be set to less than 300 ppi if they will be printed big. Also increasing the ppi makes a print smaller.
If it won't be printed and will only be displayed electronically the ppi doesn't matter.

AFAIK Canon is the only DSLR that assigns 72 ppi to photos.

Here are 2 copies of the same photo.
One that has been set to 1 ppi and a Quality setting of ZERO.
And one that has been set to 3,000 ppi and a Quality setting of Zero. Both photos have a file size of about 500 k.

Can you tell which is the 1 ppi and which is the 3,000 ppi?

kitkatdubs · Dec 1, 2015

KmH said:
No.
The ppi a photo needs to be set to depends on how big it will be printed. Some will need to be set to less than 300 ppi if they will be printed big. Also increasing the ppi makes a print smaller.
If it won't be printed and will only be displayed electronically the ppi doesn't matter.

AFAIK Canon is the only DSLR that assigns 72 ppi to photos.

Here are 2 copies of the same photo.
One that has been set to 1 ppi and a Quality setting of ZERO.
And one that has been set to 3,000 ppi and a Quality setting of Zero. Both photos have a file size of about 500 k.

Can you tell which is the 1 ppi and which is the 3,000 ppi?

I really can't tell which is which. How come canon assigns all photos to 72 ppi? Do I need to manually change all photos that I give to clients to 300 ppi in case they print them? Also, when I save a photo, from photoshop to my desktop, it show a small MB, but then when I take that image that I just saved and reopen it in photoshop, it shows a different size. Im so confused!?!?!