Pixel Enlargement?.Have I got it right?. (1 Viewer)

christineredgate · Nov 19, 2004

At last I have discovered how to enlarge a small image,by increasing the pixels from 72,the basic up to 400.I realise one can only do this on small,very clear images.So had a go on the Pied Wagtail I took today.Nigel(Blake ) did explain to me re this exercise,but until this evening could not fathom out how to do so.This is the type of image it is ideal for.So here are 2 pics of the same bird.Taken with a 20D 100-400 lens,lowest iso setting(camera pre set one),a sunny morning.The first is as the camera took the image,the second I have re sized to 400pixels.Have I gone a little over the top,or do you think the re size is okay,and looks natural.I am so chuffed to have found out how simple it is to do.I did no other enhancements pre or post,other than crop.
any advice or comments very much appreciated,thankyou.
Christine.

Saphire · Nov 19, 2004

Hey Christine I have just had a go in photoshop changing the pixel res from 72 to 150 on a photo taken from my camcorder it worked. Wow. Didn't know about that one. I have been discarding all my photos especially one's which I couldn't blowup without loosing all detail. Thanks for posting that tip.

Christine

Adey Baker · Nov 19, 2004

If you just re-size from 72 to 150 or whatever without ticking the 'Resample Image' box all you'll do is reduce the print size; i.e. if your print size is, say, 10in wide at 72ppi then re-sizing to, say, 144ppi will make it 5in wide.

To make it bigger and with more pixels you'll need to tick the 'Resample Image' box which will thus add more pixels between those already there by the dreaded method of 'interpolation' - i.e. it will 'invent' what it thinks should go between those pixels.

Nigel will recommend using 'Genuine Fractals' as the best programme to do this and this is usually the one used by professionals - there is a free trial of it available but if you don't want to purchase it and you want to use the Photoshop 'resample image' fucntion instead then the best way is to do it a bit at a time - going straight from 72 to 400 is not the best recommended way, Christine!

It's a bit boring but basically with the 'image resize' box open make sure both the 'constrain proportions' and 'resample image' boxes are 'ticked' and then just alter the resolution from 72 upwards by just a few pixels at a time - 75 - 80 - 85 - 90 etc., 'saving' every now and then to save 'RAM' space.

This can take quite a while and the difference isn't great but you're making the best of a bad job really. Some photos will look better than others - where you've got even-colour tones the interpolation will put in pixels very similar to what should be there and these will look quite good but where there's lots of fine detail the interpolation may 'guess' either right or wrong and blur the detail somewhat.

christineredgate · Nov 20, 2004

Adey,thankyou.I have tried to download the freebie from GF,spent 2 hrs,trying,it needs to go into Adobe as a plug in ,I think,by the time I had finished,no sign of GF in Adobe,had to restore the PC as Adobe's settings were all over the place,re download Acrobat reader,which I had just updated,so I decided it wasn't worth all the hassle.
So,Adey,with the pic I had increased the pixels,have I made a mess of it,does it not look better than the smaller one?.I can see it looks larger,and there are no signs of the nasty little squares.

Adey Baker · Nov 20, 2004

christineredgate said:
Adey,thankyou.I have tried to download the freebie from GF,spent 2 hrs,trying,it needs to go into Adobe as a plug in ,I think,by the time I had finished,no sign of GF in Adobe,had to restore the PC as Adobe's settings were all over the place,re download Acrobat reader,which I had just updated,so I decided it wasn't worth all the hassle.
So,Adey,with the pic I had increased the pixels,have I made a mess of it,does it not look better than the smaller one?.I can see it looks larger,and there are no signs of the nasty little squares.

Pied Wagtail is a nice contrasty subject so it will stand a bit of interpolation but it doesn't look quite as sharp as your other shot.

If you've got a few minutes to spare why not try the 'few pixels at a time' method (the posh word is 'incremental') and then compare it alongside your 72-400 shot to see if there's any noticeable difference.

As you're actually asking us to compare two different shots it's not clear if they're both as sharp as each other at the original size so this may be one reason why the second shot is not so sharp.

Andy Bright · Nov 20, 2004

GF only comes to life when you actually save the image in gf format... it's not visible as a plug-in, just a file extension when saving.

KC Foggin · Nov 20, 2004

This is interesting. Thanks for posting it Christine.

Adey, when you check the resample box should you be choosing "nearest neighbor" rather than "bicubic or bilinear" ? and if not why?

Christine, your resize certainly appears larger and as you said not pixilated at all but it does appear a bit on the soft side. Would reducing the size a bit eliminate that? I just tried it. I reduced the size a bit and used unsharp mask. It's still larger than your original but I think a bit clearer.

Adey Baker · Nov 20, 2004

'Bicubic' is the one to choose, apparently. I think it takes into account the pixels above and below as well as from side to side. presumably, the others only interpolate based on what's on one or two (bi) sides of them. 'Bicubic' is usually the default setting.

Reading through Christine's first post again, I notice that she'd done no other manipulation to the shot so the unsharp mask has indeed done the trick and improved the shot quite a lot.

KC Foggin · Nov 20, 2004

Adey Baker said:
'Bicubic' is the one to choose, apparently. I think it takes into account the pixels above and below as well as from side to side. presumably, the others only interpolate based on what's on one or two (bi) sides of them. 'Bicubic' is usually the default setting.

Thanks for the explanation Adey.

snowyowl · Nov 20, 2004

This is exciting. Does anyone know if the same thing be done using Gimp?

John N · Nov 20, 2004

I had never heard of this. Thanks very much for posting Christine, and many thanks for the tips Adey.

christineredgate · Nov 20, 2004

Thankyou Adey,for your info.Yes the next time I take a small ,but clear pic will try using smaller increments.Is that the right word!!.as to GF if anyone can tell me how to download the freebie I would be very interested.But apparently using this method in Photoshop is the next best thing,and much easier.

pete schofield · Nov 21, 2004

Here is another way to enlarge with hardly any loss of quality.

1. Under image menu choose image size when the dialogue box opens make sure resample image is turned on, and change the interpolation to bicubic smoother.

2. Switch the unit of mesurement to to percent and type 110.

3. Click ok and your image is enlarged by 10 percent.

You can keep doing this and end up with an image poster size. Having to keep inputing under image size is laborious so I suggest you create a custom action.

Sorry should have said this is with Photoshop.

Try it works, hope this is of help.

Pete

Saphire · Nov 21, 2004

Pete
Can this still be done in ver 7 of photoshop I don't seem to have a box with unit of measurements or interpolation

pete schofield · Nov 21, 2004

Saphire I haven't got 7 loaded at the mont but it should work see attached screenshot. Obviously in the percentage box put 110 don't be tempted to go any higher it degrades the image.

Pete

Saphire · Nov 21, 2004

The only difference I can see is I don't have the

Scale Styles.
Other then that it looks the same

Thanks

christineredgate · Nov 21, 2004

Saphire,be careful of the size.I have just tried to re download the copies I did plus the originals.only the originals came up as a pic on the post,the other two were just underneath,not in pic form.I did notice that the first ones were 67mb and the two enlarged ones were 1.27 GB .So I deleted the post.So obviously they do take up considerably more space even though they were resized to 800.

Saphire · Nov 21, 2004

Thanks Christine

I will have to remember that.

Christine

christineredgate · Dec 4, 2004

KC,here is the thread,hopefully this post may bring it to the top of the queue.

KC Foggin · Dec 4, 2004

And now have saved it to favorites. Thanks again Christine :t:

Pixel Enlargement?.Have I got it right?. (1 Viewer)

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