Multiple geometric transforms vs interpolation

Discussion in 'Digital Photography' started by Paul Rubin, Jan 26, 2006.

  1. Paul Rubin

    Paul Rubin Guest

    I had a picture that was slightly off-vertical. To put it on the web
    I wanted to first rotate it by a few degrees, then resize it to web
    resolution (about 0.3x). I used GIMP and selected bicubic
    interpolation for both transforms and the result still came out a
    little bit blurry. I'm wondering if the interpolations (which by
    definition computes each destination pixel from several source pixels)
    get worse as they are compounded. Maybe photo editors should keep
    track of these transformations as you do them on-screen, and combine
    them into a single transformation matrix (or different matrices for
    different regions of the picture as you cut and paste). Then at the
    end you'd re-transform the picture (i.e. go from the initial to final
    picture) in a single pass, without all the intermediate steps. In
    that way you'd only be interpolating once instead of several times.

    Do any editing programs do that? Is there a way to get GIMP to do it?
    Does it make sense?
     
    Paul Rubin, Jan 26, 2006
    #1
    1. Advertising

  2. Paul Rubin

    Scott W Guest

    Paul Rubin wrote:
    > I had a picture that was slightly off-vertical. To put it on the web
    > I wanted to first rotate it by a few degrees, then resize it to web
    > resolution (about 0.3x). I used GIMP and selected bicubic
    > interpolation for both transforms and the result still came out a
    > little bit blurry. I'm wondering if the interpolations (which by
    > definition computes each destination pixel from several source pixels)
    > get worse as they are compounded. Maybe photo editors should keep
    > track of these transformations as you do them on-screen, and combine
    > them into a single transformation matrix (or different matrices for
    > different regions of the picture as you cut and paste). Then at the
    > end you'd re-transform the picture (i.e. go from the initial to final
    > picture) in a single pass, without all the intermediate steps. In
    > that way you'd only be interpolating once instead of several times.
    >
    > Do any editing programs do that? Is there a way to get GIMP to do it?
    > Does it make sense?

    What you are saying makes sense on a theoretical basis but on a
    practical level it normally will not have that much effect.

    In Photoshop Elements III I can do a rotate and resize at the same time
    using the crop tool, I don't know if gimp can do this.

    Scott
     
    Scott W, Jan 27, 2006
    #2
    1. Advertising

  3. Paul Rubin

    Tesco News Guest

    "Scott W" <> wrote in message
    news:...
    > Paul Rubin wrote:
    >> I had a picture that was slightly off-vertical. To put it on the web
    >> I wanted to first rotate it by a few degrees, then resize it to web
    >> resolution (about 0.3x). I used GIMP and selected bicubic
    >> interpolation for both transforms and the result still came out a
    >> little bit blurry. I'm wondering if the interpolations (which by
    >> definition computes each destination pixel from several source pixels)
    >> get worse as they are compounded. Maybe photo editors should keep
    >> track of these transformations as you do them on-screen, and combine
    >> them into a single transformation matrix (or different matrices for
    >> different regions of the picture as you cut and paste). Then at the
    >> end you'd re-transform the picture (i.e. go from the initial to final
    >> picture) in a single pass, without all the intermediate steps. In
    >> that way you'd only be interpolating once instead of several times.
    >>
    >> Do any editing programs do that? Is there a way to get GIMP to do it?
    >> Does it make sense?

    > What you are saying makes sense on a theoretical basis but on a
    > practical level it normally will not have that much effect.
    >
    > In Photoshop Elements III I can do a rotate and resize at the same time
    > using the crop tool, I don't know if gimp can do this.
    >
    > Scott
    >


    Photoshop and Elements can also do it by using the Crop Tool, and in less
    clicks.

    The real answer is to use a non lossy format (Tiff ) for Edits which affect
    pixels. But it is actually the "Saves" following the Edits which cause most
    of the problem.

    If it was an image from a Digital Camera, it could also be that the Camera
    was set to apply too much sharpening to the Jpeg. Sharpening is almost
    always best kept to the very end of the workflow.

    Roy G
     
    Tesco News, Jan 27, 2006
    #3
  4. Paul Rubin

    Paul Rubin Guest

    "Tesco News" <> writes:
    > > In Photoshop Elements III I can do a rotate and resize at the same time
    > > using the crop tool, I don't know if gimp can do this.

    > Photoshop and Elements can also do it by using the Crop Tool, and in less
    > clicks.
    > The real answer is to use a non lossy format (Tiff ) for Edits which affect
    > pixels. But it is actually the "Saves" following the Edits which cause most
    > of the problem.


    I'm talking about doing multiple edits in one session, not saving
    between the edits. Question is whether the multiple interpolations
    messes up the image.

    Fancier editing might mean an even longer chain of interpolations:

    - rotate image
    - adjust perspective using grid lines in in editor
    - rotate post-perspective-adjusted image
    - scale image and paste a selection from it into a composite image
    - do similar steps with some other image, pasting into same composite
    - scale the composite image for the web

    Also, when editing it's nice to be able to see all the intermediate steps.

    The original pic was a fine-resolution jpeg, if that matters.
     
    Paul Rubin, Jan 27, 2006
    #4
  5. Paul Rubin

    Guest

    BEEN DREAMING OF LIVING THE GOOD LIFE, ON YOUR TERMS? YOU CAN DO
    THIS!


    You will now become part of a Mail Order business. In this business
    the
    product is not solid or tangible, it's a service. You are in the
    business
    of developing Mailing Lists. You deal with information, and
    information is
    power. Many large corporations are happy to pay vast amounts for
    quality
    lists. However, the money made from the mailing lists is secondary to
    the
    income which is made from people like you and me asking to be included
    on
    such a list.


    I used to work my butt off for someone else, but not any more. Getting
    on
    to the internet changed everything. I came across an article that said
    you
    could make thousands of dollars within weeks with a once only
    investment of
    $6.00! "Yeah, right, what a scam," is what I thought. I was skeptical
    to
    say the least. Still, I was curious. I figured I could stand to lose
    six
    bucks, so I kept reading.


    I'm pretty glad I did. All you had to do was send $1.00 to the 6 names
    at
    the addresses listed in the article. Then, you placed your name and
    address
    at the bottom of the list at position #6, and posted the article to at
    least
    200 newsgroups.


    I felt pretty silly after I'd sent the letters, and it took a bit of
    time to
    post the message to all those newsgroups. To be honest, I pretty much
    forget about the whole deal there and then. "It's only six dollars. No
    big
    deal."


    Was I in for a surprise. GUESS WHAT! Within 7 days, I started getting
    money
    in the mail! It was amazing! I figured it would end, but it didn't.
    The
    money just kept rolling in. I made about $18.00 in the first week. By
    the
    end of the second week I'd made a total of over $980. $10,328 in week
    three, and it just went on and on. This is now my fifth month and I'm
    sitting on about $273,000. Needless to say I quit my job a while back.
    (I
    used to work as a computer software manager)


    It was certainly worth the $6.00 and change for the stamps. I've spent
    more
    than that on the lottery, without a cent to show for it!!


    Print a copy of this article, so you can refer back to it, or cut and
    paste
    it to Notepad or Word. The process is very simple and is comprised of
    3
    easy steps. If you're wondering why I'm letting you in on this, I'll
    explain it to you shortly. Bear with me. This works.


    STEP 1: Get 6 separate sheets of paper and write the following on each;

    "PLEASE PUT ME ON YOUR MAILING LIST."


    Get 6 US$1.00 bills (or the equivalent in your local currency) and
    place a
    dollar and a note in each of the 6 envelopes. Fold the bill into the
    paper
    in order to prevent it from being seen, and possibly stolen.


    You should now have 6 sealed envelopes, each containing a dollar and
    the
    note. Don't forget to add your name and address.


    Mail the 6 envelopes to the following addresses:


    #1 R. Arambasic, 9 Ashmore St, Brunswick, VIC, Australia 3056
    #2 S. Vouge, P.O. Box 5173, New York, N.Y. 10163, USA
    #3 R. Dumancic, Mlinarska 22A, Zagreb, 10000, Croatia
    #4 D. Lozina, 128 Nicholson St, Fitzroy, VIC, Australia 3065
    #5 B. Spaleta, 39 Stewart Gve, Campbellfield, VIC, Australia 3061
    #6 J. Wurdemann, P.O. Box 912, North Branch, MN. 55056, USA


    STEP 2: Take name #1 off the list above, move the other names up (6
    becomes
    5, 5 becomes 4, etc...) and add YOUR name as number 6 on the list.
    STEP 3: Post your amended article to at least 200 newsgroups. (There's
    heaps
    out there) All you need is 200, but the more you post, the more money
    you
    make!


    ********* HOW TO POST TO NEWSGROUPS (It's easy) *********


    1. You don't need to re-type this entire letter to do your own posting.
    Cut
    and paste this letter to your Notepad. 2. Remember to eliminate the #1

    position, move everyone up a spot (re-number everyone else's
    positions),
    and add yourself as #6. 3. Save your new notepad file as a .txt file.
    If
    you want to do your postings in different sittings, you'll always have
    this
    file to go back to.


    *** NETSCAPE USERS ***


    Step 4. Within the Netscape program, go to the pull down window
    entitled
    'Window' select 'NetscapeNews'. Then from the pull down menu
    'Options',
    select 'Show all Newsgroups'. After a few moments a list of all the
    Newsgroups on your server will show up. Click on any newsgroup you
    desire.
    >From within this newsgroup, click on the 'TO NEWS' button, which should

    be
    in the top left corner of the newsgroups page. This will bring up a
    message
    box.


    Step 5. Fill in the Subject. This will be the header that everyone sees
    as
    they scroll through the list of postings in a particular group.


    Step 6. Highlight the entire contents of your .txt file, and cut and
    paste
    it the letter into the body of your posting.


    Step 7. Hit the 'Send' Button in the upper left corner. You're done
    with your
    first post! Congratulations...


    *** INTERNET EXPLORER USERS ***


    Step 4. Go to newsgroups and select 'Post an Article'.
    Step 5. Fill in the subject.
    Step 6. Same as #6 above
    Step 7. Hit the 'Post' button.


    Alternatively, you can use a program like Forte Agent, which you can
    find on
    the Web.


    THAT'S IT! All you have to do is jump to different newsgroups and post
    away,
    after you get the hang of it. It takes about 30 seconds for each
    newsgroup!


    **REMEMBER, THE MORE NEWSGROUPS YOU POST TO, THE MORE MONEY YOU'LL
    MAKE!!
    POST A MINIMUM OF 200**


    There you go! You'll begin receiving money from around the world
    within
    days! You may eventually even want to rent a P.O. Box due to the large

    amount of mail you'll receive. Should you wish to stay anonymous, you
    may
    use a pseudonym, as the postman will deliver it just the same.


    **MAKE SURE ALL THE ADDRESSES ARE CORRECT.**


    So, why am I letting you in on this. Let me explain.


    Out of 200 postings, say I receive only 5 replies. I make $5.00 with
    my
    name at #6 on the letter. Now, if each of the 5 individuals who sent
    me
    $1.00 make the minimum 200 postings, with my name at #5, and only 5
    people
    respond to each of the original 5, that's another $25.00 for me. Now
    those
    25 each make 200 posts with my name at #4, and with 5 replies each, I
    earn
    an additional $125.00! Those 125 turn around and post the minimum 200
    with
    my name at #3 and receive 5 replies each, I make $626.00 more! Get the
    picture? Five responses is actually a below norm response rate. The
    average is about 15 to 25. For example, here's what you can expect to
    earn from 15 responses:


    at #6 $15.00 at #5 $225.00 at #4 $3,375.00 at #3 $50,625.00 at
    #2
    $759,375.00 at #1 $11,390,625.00


    When your name is no longer on the list, you just take the latest
    posting in
    the newsgroups, and send out your $6.00 to names on the list, putting
    your
    name at number 6 again (which is what I'm doing), and start posting
    again.


    The thing to remember is that thousands of people all over the world
    are
    joining the internet and reading these articles everyday, just as you
    are
    now!!


    Can you afford $6.00? I believe so. (I just didn't buy lunch that day)



    People have said, "what if the plan is played out and no one sends you
    the
    money? Doesn't matter. There are tons of new honest users and new
    honest
    people who are joining the internet and newsgroups everyday, willing to
    give
    it a try? Estimates are at 20,000 to 50,000 new users daily.


    This will work for you. Be honest, be fair. Remember, what goes around

    comes around.
     
    , Jan 27, 2006
    #5
  6. Paul Rubin

    Ron Hunter Guest

    Paul Rubin wrote:
    > I had a picture that was slightly off-vertical. To put it on the web
    > I wanted to first rotate it by a few degrees, then resize it to web
    > resolution (about 0.3x). I used GIMP and selected bicubic
    > interpolation for both transforms and the result still came out a
    > little bit blurry. I'm wondering if the interpolations (which by
    > definition computes each destination pixel from several source pixels)
    > get worse as they are compounded. Maybe photo editors should keep
    > track of these transformations as you do them on-screen, and combine
    > them into a single transformation matrix (or different matrices for
    > different regions of the picture as you cut and paste). Then at the
    > end you'd re-transform the picture (i.e. go from the initial to final
    > picture) in a single pass, without all the intermediate steps. In
    > that way you'd only be interpolating once instead of several times.
    >
    > Do any editing programs do that? Is there a way to get GIMP to do it?
    > Does it make sense?

    In most cases, it is better to crop than rotate as cropping will not
    markedly degrade the image, just discards a few pixels.
     
    Ron Hunter, Jan 28, 2006
    #6
  7. Paul Rubin

    Guest

    Paul Rubin wrote:
    > I had a picture that was slightly off-vertical. To put it on the web
    > I wanted to first rotate it by a few degrees, then resize it to web
    > resolution (about 0.3x). I used GIMP and selected bicubic
    > interpolation for both transforms and the result still came out a
    > little bit blurry.


    Since it is downsized a lot, 3x, the rotate degrading should be
    neglectable. The blurry probably resulted from the bicubic resampling.

    > I'm wondering if the interpolations (which by
    > definition computes each destination pixel from several source pixels)
    > get worse as they are compounded. Maybe photo editors should keep
    > track of these transformations as you do them on-screen, and combine
    > them into a single transformation matrix (or different matrices for
    > different regions of the picture as you cut and paste). Then at the
    > end you'd re-transform the picture (i.e. go from the initial to final
    > picture) in a single pass, without all the intermediate steps. In
    > that way you'd only be interpolating once instead of several times.
    >
    > Do any editing programs do that?


    Photoshop layers are supposed to work this way. Every editing is in a
    separate layer. You collapse the layers to get the end result.

    I am not sure whether these particular editings can be layers in the
    latest version of Photoshop.

    http://digitcamera.tripod.com/#slr
     
    , Feb 10, 2006
    #7
  8. Paul Rubin

    Paul J Gans Guest

    wrote:
    >Paul Rubin wrote:
    >> I had a picture that was slightly off-vertical. To put it on the web
    >> I wanted to first rotate it by a few degrees, then resize it to web
    >> resolution (about 0.3x). I used GIMP and selected bicubic
    >> interpolation for both transforms and the result still came out a
    >> little bit blurry.


    >Since it is downsized a lot, 3x, the rotate degrading should be
    >neglectable. The blurry probably resulted from the bicubic resampling.


    >> I'm wondering if the interpolations (which by
    >> definition computes each destination pixel from several source pixels)
    >> get worse as they are compounded. Maybe photo editors should keep
    >> track of these transformations as you do them on-screen, and combine
    >> them into a single transformation matrix (or different matrices for
    >> different regions of the picture as you cut and paste). Then at the
    >> end you'd re-transform the picture (i.e. go from the initial to final
    >> picture) in a single pass, without all the intermediate steps. In
    >> that way you'd only be interpolating once instead of several times.
    >>
    >> Do any editing programs do that?


    >Photoshop layers are supposed to work this way. Every editing is in a
    >separate layer. You collapse the layers to get the end result.


    >I am not sure whether these particular editings can be layers in the
    >latest version of Photoshop.


    >http://digitcamera.tripod.com/#slr


    Irfanview has a somewhat more sophisticated Lanczos filter
    for doing shrinking. It uses more points and, I think, can
    detect sharp edges. I've used it and like it.

    Since Irfanview is free, why not give it a try?

    ----- Paul J. Gans
     
    Paul J Gans, Feb 10, 2006
    #8
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Ed

    Help Identify Geometric Shape

    Ed, Oct 16, 2003, in forum: Computer Support
    Replies:
    5
    Views:
    717
    DaveW
    Oct 17, 2003
  2. Tim923

    geometric mean of 2.35 and 4/3

    Tim923, Jun 23, 2004, in forum: DVD Video
    Replies:
    58
    Views:
    1,621
    Richard C.
    Jul 4, 2004
  3. Replies:
    1
    Views:
    358
    Paul Heslop
    May 5, 2006
  4. Replies:
    13
    Views:
    625
    BJ in Texas
    Sep 11, 2006
  5. Lawrence D'Oliveiro

    All-or-nothing transforms

    Lawrence D'Oliveiro, Mar 6, 2009, in forum: NZ Computing
    Replies:
    0
    Views:
    338
    Lawrence D'Oliveiro
    Mar 6, 2009
Loading...

Share This Page