WPF - World Photography Forum
Home Gallery Register FAQ Calendar Search Today's Posts Mark Forums Read

Welcome to World Photography Forum!
Welcome!

Thank you for finding your way to World Photography Forum, a dedicated community for photographers and enthusiasts. There's a variety of forums, a wonderful gallery, and what's more, we are absolutely FREE. You are very welcome to join, take part in the discussion, and post your pictures!

Click here to go to the forums home page and find out more.
Click here to join.


Go Back   World Photography Forum > Photography Technique > The Digital Darkroom


The Digital Darkroom The In-Computer editing forum.

INTERPOLATION. Help Please.

Reply
 
Thread Tools
  #1  
Old 11-08-06, 17:55
G B-S. G B-S. is offline  
Member
 
Join Date: Dec 2005
Location: Teesdale
Posts: 24
Default INTERPOLATION. Help Please.

Dear all,

I need help here.

I use PS7 and on occasion would like to enlarge an image, a crop, without loosing quality.
Could a kind subscriber hold my hand and guide me though the subject of interpolation.
Please be patient this is a new adventure about which I know nothing.

Regards.
G B-S.
Reply With Quote
  #2  
Old 12-08-06, 02:18
nirofo's Avatar
nirofo nirofo is offline  
Senior Member
 
Join Date: Dec 2005
Location: North Scotland
Posts: 798
Default

Hi G B-S

I don't use Photoshop 7 anymore, I now use CS2, however, I believe the method of changing the size of an image is still the same in all versions.

First open your preferred image, click on Image on the Tools Menu, select Image Size from the drop down menu.

Now if you want the proportions of the photo to remain the same but just want to increase the size, make sure you have Constrain Proportions and Resample Image boxes ticked.

In Document Size enter the new size you would like the photo to be, (only change one dimension).

If you are resizing for the web leave the resolution at 72, if you are resizing for printing, then resize to a minimum of 200 pixels/inch, preferably 300 pixels/inch.

If you don't want to keep the original proportions then you will need to untick Restrain Proportions and enter both sets of dimensions in Document Size.

When you have done this your file size will have increased also, make sure you have enough space on your disk, then save your new sized photo with a new name, that way you won't lose your original file.

Hope this helps.

nirofo.
Reply With Quote
  #3  
Old 12-08-06, 09:14
Adey Baker's Avatar
Adey Baker Adey Baker is offline  
Senior Member
 
Join Date: Dec 2005
Location: Hinckley, Leics., UK
Posts: 965
Default

It just needs adding that the amount of interpolation you need will affect the final quality of the image.

There are software programs available such as 'Genuine Fractals' that claim to make a better job of it than the basic interpolation in PS but all must, by definition, lose a bit of quality somewhere as they're all sort of 'stretching the original image and adding bits in' to make it bigger.
__________________
Adey

http://www.birdforum.net/pp_gallery/...00/ppuser/1805

'Write when there is something you know: and not before: and not too damned much after' Ernest Hemingway
Reply With Quote
  #4  
Old 12-08-06, 12:09
Don Hoey's Avatar
Don Hoey Don Hoey is offline  
Senior Member
 
Join Date: Dec 2005
Location: Norfolk
Posts: 4,462
Default

Quote:
Originally Posted by Adey Baker
It just needs adding that the amount of interpolation you need will affect the final quality of the image.

There are software programs available such as 'Genuine Fractals' that claim to make a better job of it than the basic interpolation in PS but all must, by definition, lose a bit of quality somewhere as they're all sort of 'stretching the original image and adding bits in' to make it bigger.
I agree there will be some loss as you are adding pixels that did not exist in the origional and these are only an estimate by the program of what it thinks should be there.

I have used Genuine Fractals and with my very poor knowledge of pp at the time managed results that amazed me. This is a link to an earlier posting in the RAW or JPEG thread. http://www.worldphotographyforum.com...p?t=662&page=8 Post 73

I have tried increasing size in standard imaging program in 5% increments with good results but that takes ages as lots of steps involved. All a long time ago now, so I would have to revisit the subject afresh to be any real help.

Don
Reply With Quote
  #5  
Old 12-08-06, 12:35
G B-S. G B-S. is offline  
Member
 
Join Date: Dec 2005
Location: Teesdale
Posts: 24
Default

Nirofo and Adey,

Thank you for the reply,

I have had a go following your instructions. The results were interesting, as you say a large file and a degradation in the quality.

I used the bicubic option as it was the default. Presumably this is best.

Genuine Fractals is new to me. Have either of you used this software?

Finally off topic – Nirofo is your avatar a Sea Eagle?

Cheers Gordon.
Reply With Quote
  #6  
Old 12-08-06, 13:14
Adey Baker's Avatar
Adey Baker Adey Baker is offline  
Senior Member
 
Join Date: Dec 2005
Location: Hinckley, Leics., UK
Posts: 965
Default

Quote:
Originally Posted by G B-S.

I used the bicubic option as it was the default. Presumably this is best.
Yes - the 'cubic' bit means it's taking information from all the adjacent pixels to form the new pixels.

I haven't used GF (although I've got a free sample CD somewhere that allows 30 free goes before it cuts out - and no doubt then keeps reminding you to buy the damned thing ).

'Amateur Photographer' did a test some time back and GF came out best with the 'bit at a time' method described above by Don coming in second and the basic bi-cubic third, though with the quality of magazine reproduction I don't think there was that much difference visible to the reader - you have to trust the comments of the reviewer.

Whichever method you use, the best results will come when you use it to make a larger print than normal - big prints are usually viewed from a greater distance where the loss of resolution won't be too visible! When you try to enlarge a cropped area you're starting with the resolution 'stretched' to begin with and you'll probably be looking at it from the same distance as your full-frame images.
__________________
Adey

http://www.birdforum.net/pp_gallery/...00/ppuser/1805

'Write when there is something you know: and not before: and not too damned much after' Ernest Hemingway
Reply With Quote
  #7  
Old 12-08-06, 13:34
nirofo's Avatar
nirofo nirofo is offline  
Senior Member
 
Join Date: Dec 2005
Location: North Scotland
Posts: 798
Default

Quote:
Originally Posted by G B-S.
Nirofo and Adey,

Thank you for the reply,

I have had a go following your instructions. The results were interesting, as you say a large file and a degradation in the quality.

I used the bicubic option as it was the default. Presumably this is best.

Genuine Fractals is new to me. Have either of you used this software?

Finally off topic – Nirofo is your avatar a Sea Eagle?

Cheers Gordon.

Hi Gordon

Interesting that you think your results so far are interesting, large file and a degredation of image quality. What increase in size are you talking about, I quite regularly scan my slides at approx 28mb and interpolate to 40mb plus using either Photoshop CS2, or Genuine Fractals 4, personally I can't see the difference in quality only in file size? These files are sent to various publishers and Photo agencies without comment, other than most now prefer to receive submissions from digital cameras rather than scanned images!

On another tack, I was asked recently to supply a photograph urgently of a male Blackcap feeding young in the nest for inclusion in a glossy brochure, the only image I had available immediately was a scan I had done for the web some time ago, file size was 193kb jpg. I opened this image in Photoshop, changed the size to 10x15cm x300 pixels/inch, now = 5.99mb. This image was used commercially and was more than adequate for reproduction purposes. This of course far exceeds anything needed for the web.

Attached is the image in question.

My avatar is a flight shot of a Griffon Vulture, taken in Andalucia, Spain using a Tokina 75-300 zoom at 300 f5.6 on a Nikon F90X, film was Fuji Sensia 100 pushed to 250ASA and processed at 200ASA.

nirofo.
Attached Images
File Type: jpg Blackcap male feeding young.jpg (193.0 KB, 15 views)

Last edited by nirofo; 12-08-06 at 13:38.
Reply With Quote
  #8  
Old 12-08-06, 18:39
G B-S. G B-S. is offline  
Member
 
Join Date: Dec 2005
Location: Teesdale
Posts: 24
Default

Dear all -
Thank you for all the trouble you are going to, and the time.
After reading your letters again I have had more success and I am now going to attempt to attach a photograph - the original picture and a crop of the eagle interpolated to 800 pixels.
Comments and further advice please!
Cheers - Gordon.
Attached Images
File Type: jpg 959W4817a.jpg (324.7 KB, 20 views)
File Type: jpg 959W4817d.jpg (312.3 KB, 24 views)
Reply With Quote
  #9  
Old 12-08-06, 19:48
robski robski is offline
Senior Member
 
Join Date: Dec 2005
Location: Kent UK
Posts: 3,739
Default

Gordon

What may of helped in this case before you enlarged was to us a noise reduction program such as Picture Cooler or Neatimage.

Below is an example from your first image and enlarge 100%. So on your original file the result should be quiet good.
__________________
Rob

-----------------------------------------------------
Solar powered Box Brownie Mk2

Captain Sunshine, to be such a man as he, and walk so pure between the earth and the sea.

WPF Gallery
Birdforum Gallery
http://www.robertstocker.co.uk updated

Last edited by robski; 26-07-11 at 22:34.
Reply With Quote
  #10  
Old 12-08-06, 20:36
Don Hoey's Avatar
Don Hoey Don Hoey is offline  
Senior Member
 
Join Date: Dec 2005
Location: Norfolk
Posts: 4,462
Default

Gordon,

Having seen what Rob has done it may be worth posting a similar crop from the origional image with as little compression as possible.

Lots of clever people here who can then play with the image and give best suggestions.

Don
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 01:51.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.