Question about Resolution Quality

Jamey_29

I had an important job done by a photographer during the summer. I received a digital package which had the images on a cd. The images were in Jpeg format all approx 1.5MB in size with a resolution of what I thought a 6 X 4 should be. I asked the photographer what was the deal that the images supplied seemed to be in low resolution.
I was told to use photoshop or the likes to resize the images when needed. If i wanted a 8X 10 resize it individually and so on. Sure enough the size of the file and resolution increases using the resize tool in photoshop. But thats not right is it??? The guy is a reputible businness man with his own shop. I would love to hear peoples opinions on this?

PCPhoto

messing about with JPG files will damage the files and ultimately the image - the original photographer should have provided large enough files to do this.

can you post a sample image on a hosting site and people here can download and see what you are talking about - for me the image file size seems low but sometimes people take different readings for file size (ie. some people see it as the size that the image says according to photoshop - others think its the size of the image after its compressed by photoshop - others again will say its the size in MB that the image says on the desktop when you click on file properties etc etc)

its hard to understand without an example.

when I look at an unopened file on my desktop it says 7.4MB (some say higher some slightly lower...but you get the idea) - when I open this image in photoshop if I look at the bottom of the screen photoshop tells me the image is 45.7/45.7M .....then if I save the image changing the filename only - image quality 8/High on photoshop the image is now 1.2MB on my desktop.

have you got photoshop or photo editing software ?

McVitae

What was the pixel resolution of the images?

Forgive me is some of the following is obvious
In strict terms the resolution of the image (obviously the number of pixels across x number of pixels down) is nothing to do with image size per say. Printers simply have a certain PPI (Pixels per inch) which means that if you have a printer set to 300 PPI, then without resizing it, an image of 1800 X 1200 (300x6 X 300x4) should produce a standard 6x4 inch print. Printers usually have the capability to change the PPI with higher than 300 PPI being a good photo print quality (Please someone let me know if my calculations are out of whack ).

The size of 1.5 MB isn't a great indicator because image size of jpeg images is a function of
1. pixel resolution
2. compression algorithm type (i.e. lossy, lossless etc..)
3. how aggressive the compression is (this can be set usually with a slider from 0-100 when you save a jpeg)
4. The contents of the image (This is quirk of the JPEG compression algorithm)

On resizing. Try to start with a big image and resize it smaller. Otherwise you are making up information to fit in the gaps. Also use the most processing intensive resize algorithm you can find. Usually bicubic interpolation if the option is there.
If resizing to a dimension that is not of the same ratio as original resolution, either use a content aware scaling (photoshop CS5 I think) or don't bother .

Jamey_29

I have the photos saved to my desktop at home so can PM a picture later on. Thanks. The properties on average were 1200 X 1500 resolution according to windows. I have a portable version of Photoshop.

Corkbah

whats a portable version of photoshop ?

its a programme ... can be uploaded to a PC/Mac and taken anywhere.

Gumbo

i recently got a gift of some pixe photos for the baby, after which we bought the CD with all photos and copyright.

The cd contains the photos which are compressed to approx 5MB in size, but when i open them in Photoshop they un-compress to 50MB in size.

I copied them from the CD and uploaded to Flickr, and will include one below for comparisons :


Lucas October 2011 by kceire, on Flickr

Kenny Logins

Corkbah wrote: »

whats a portable version of photoshop ?

its a programme ... can be uploaded to a PC/Mac and taken anywhere.

Runs from USB stick without installing?

Jamey_29

Right...Ive uploaded a typical photo from the day. I have included a snaphot of what i see in windows. Appreciate your opinions on this.



http://www.flickr.com/photos/69674730@N06/6333416754/

http://www.flickr.com/photos/69674730@N06/6333423388/lightbox/

Jamey_29

Looks like Flickr is resizeing before publishing. I cam email the photo also?

AnCatDubh

as a general rule of thumb divide the dimensions of the image (1500x1200 or whatever they happen to be) by 300 (sometimes quoted as 320, 340) and that should give you an 'ideal' size in terms of the inch dimensions of the resulting print. Now, in reality you can get away with a good deal less and dividing the image dimensions by 200 isn't unheard of and generally will produce images which are good enough in quality for the resulting size.

Resizing the image from a jpg to a larger size for example you want your 1500x1200 image to be 3000x2400 to get the required size, may work in technical terms but you may be left with resulting image quality issues as the program which resizes make a few calculated guesses about what would have been there had the image been that big in the first place. You might get away with it but you are always best working from the largest available image and sizing downwards rather than upwards.

All that said and it is also important to remember that there are multiple variables at play including things like the processing/printing equipment, the selection of paper being used and its ability to soak ink or otherwise. For example, you will get away with less than the 200 quoted in the above calculations if you are going to do a canvas print.

If as a result of the calculations suggested above, your images appear too small in resulting inch dimensions, then i'd suggest asking your photographer for larger versions of the images suitable for whatever size you require.

Jamey_29

Thanks. The deal we arranged was for a Digital package. Which included Cropped, corrected high resolution photos. I just hope I can get this sorted and he still has the raw images.

McVitae

ok i took a look at the image you sent on. They are 1500 x 1200 jpegs.

First off this is a natural aspect ratio of 5x4. In fact at 300 PPI printing this will print perfectly to a 5 inch x 4 inch print. No matter what you should maintain this 5:4 ratio and not resize them to print on 6x4 as as it will stretch the image (unless you want to use content aware scaling but these types of images wont respond that well to content aware scaling because of their busy content).

Printing a 10x8 inch picture is possible as it maintains the 5:4 ratio however it would either require the printer to be lowered to 150 PPI (which is ok but isnt a great print quality) or else you could resize the image in photoshop to 3000x2400 pixels. However resizing up is not ideal at all as the computer will need to make up the missing pixels and the quality is reduced somewhat.

If I was printing a 10x8 inch of these I would ask the photographer to send me the images at the higher res of 3000x2400 or more. This isnt a lot to ask I think as he/she originally sent you on only a 1.8megapixel image (1500 x 1200=1.8million). Especially when you consider that their originals were probably up on 10 megapixels or more. The key here is that resizing down from a larger image is ALWAYS better than resizing up from smaller image.

Hope this helps.

Jamey_29

Thanks McVitae. This is what I thought from the start...when i queryied it he seemed to have such a good explanation. We paid a small fortune to get high res. photos of the day and get our album done at a later stage. I am starting to think he wants us to go back to him for the prints....I have everything in writing though Thanks again.