DPI (dot per inch) dan kaitannya dengan dunia digital photo

[cgmulia]

ha.. memandangkan aku baru terperasan masa raya baru ni... aku mula tertanya-tanya bgmana hasil akibat pengaruh dpi ni

inttrooo sikit pasal dpi yg aku tau...
asalnya dlm dunia grafik dpi ini memainkan peranan yg penting. aku nak terang pun aku kurang mahir dlm hal2 ni... cuma yg aku tau.. kalau 72 dpi, ia lebih sesuai utk web output. kalau korang perasan.. masa ita guna PS, setting default utk wallpaper adalah 72 dpi jek. dan adalah disarankan supaya gmbr2 web menggunakan setting ini kerana lebih ringan dan ia hanya sekadar paparan sahaja.
aku penah menuntut ngan sifoo aku dulu pasal grafik dan web development dan antara saranan beliau adalah seperti diatas memandangkan kita mahukan web kita mesra pengguna. namun begitu kita juga menitik beratkan saiz fail grafik itu sendiri supaya ringan dan mudah 'loading'. utk pengetahuan semua (kepada yg belum tahu lah) gmbr yg besar tidak akan memberi kesan yang nyata bila dikecilkan namun jika gmbr yg kecil dibesarkan ia akan mempamerkan satu kecacatan yg nyata. so, kalau kita menggunakan dpi 72 (setting biasa) utk printing... kita akan hadapi masalah dimana gmbr itu akan pecah sedikit bila diprint utk saiz yg besar. kadang-kala kita tak perasan kerana ia perlu diperhatikan dengan lebih dekat utk melihat kesannya.

saya perasan semua ni bila saya review gmbr2 dari 3 camera saya iaitu cybershot dsc P10, Fz20, dan D70s.

p10 dan fz20 mempunyai dpi yg rendah iaitu 72 dpi sahaja... maybe untuk 3R atau 4R tak nampak kesannya. tp bila menggunakan 8R, ia akan jelas sedikit kecacatannya. namun begitu ia tidak lah memberi kesan kepada org2 yg hanya mau tgk... bukan org pure grafik!. utk d70s, saya lihat ia mempunyai 300dpi. saya megetahui ttg law printing ni apabila membuat cover dokumentasi KENYIR CHALLENGE 2003 utk kementerian Pelajaran Malaysia daripada sifoo saya. beliau mencadangkan sekurang2nya utk printing, mesti 150dpi dan ke atas. dan juga sepanjang saya buat banting(cam benner tu.. tak tau eja camne) utk sekolah saya dulu, saya terpaksa menggunakan setting 300 dpi, utk cetakan menggunakan imej berasaskan PS. fail yg dihasilkan amat besar kadangkala merangkak PC dengan saiz sebenar.
saya terperasan bila melihat gmbr kawin yg telah saya print 8R hasil fz20, DSC-P10 dan gmbr family d70s. amat berbeza sekali outputnya.

itu lah yg saya tahu ttg pengaruh dpi pada digital photography ni.
nanti saya add lagi jika ada info2 ttg dpi ni.. la ni sibuk nak exam.... so hanya bagi apa yg dah ada dlm otak ni..

kalau ada salah konsep ke.. silap maklumat ke ... bgtau lah.. saya pun bukanlah org yg sempurna..

org lain ada info?? tambah ... tambah... ilmu ni!!!!!!

[cgmulia]

tambah sikit

dots-per-inch (DPI)


Dots-per-inch is a metric from offset printing that describes the reproduction quality of the printed image. Printed images are commonly created using a dot halftone pattern. The smaller the halftone dots, the greater the number of dots that can be printed within a set area and the finer the reproduction quality.
Screen resolution

In comparison to print media, screen-based images are of a much lower quality (resolution). The finest ‘dot’ is limited to a single pixel. Images optimised for screen display are usually 72 DPI—a quarter the typical resolution of a printed image. This lower resolution is the reason why images from webpages appear ‘blocky’ (pixellated) when printed.

Photographic images are typically printed at 300+ DPI. At around 600 DPI the halftone pattern is no longer discernible to the unaided human eye.

[cgmulia]

dan lagi..

"The Resolution's Too Low"
by Andrew Starling

If you've never heard this expression, then you've probably never tried to get a screenshot or graphic from the Web printed in a brochure or magazine.
May 31, 2000

"No, sorry, we can't print that, the resolution's way too low. It's only 72 ppi and we print at 100% dpi. And if we try to bring the resolution up, your picture will be way too small."

Oh dear. If you want to get your precious screenshot/Web-graphic into print, you've now got about twenty minutes of explaining to do. Here's what you need to know if you're going to convince anybody that it's possible.

(If you're in a rush, just skip to the brief pointers at the end.)
Mediocrity

Let's start with the big grain of truth contained in that rejection you just heard. Web graphics and screenshots are pretty lousy quality. They don't contain anything like the amount of information you'll find in a print graphic or a good scan. You can guarantee your final image won't look brilliant. And if the final print size is large, you'll be able to see distinct pixellation, probably more than you thought was there when you viewed the picture on screen.

But if you're prepared to accept these quality limitations, you should be able to print what you can see on a computer screen. After all, if you took a good photograph of a screen and scanned it, you'd get to see what you wanted. And your screenshot or Web graphic contains all the information you need for print reproduction, it's just a matter of formatting it properly so it comes out in a way that's as good as a scanned photograph.

A bit of pixellation isn't much of a problem if you're printing a screenshot. Everybody knows that computer screens show rough pictures, so their expectations aren't high. Having said that, aiming for full screen-size reproduction is a little adventurous. Half size or a quarter is more reasonable. And if you try to take a Weh-graphic and pass it off as a proper print graphic, you'll soon run into quality problems. Something like a company logo will usually need to be redrawn if it's transferred from the Web to print, unless its size is greatly reduced.
Keeping Quality Up

The key to quality is to transfer the screenshot or graphic into a print format in the best way possible. You'll be well placed to do this if you understand something about pixels, Pixels Per Inch (PPI) and Dots Per Inch (DPI), though it may be possible to get away without this knowledge.

Pixels and ppi are covered in detail in a separate article, The Mad, Mad World of Pixels Per Inch. Briefly, Web graphics and screenshots are made up of dots of colour called pixels, and they usually contain 72 pixels per inch, though other resolutions are common

Dots Per Inch (dpi), on the other hand, is a property of a print graphic and determines how it prints - its size and quality. Printing isn't done in continuous colour, it's done with individual dots of Cyan, Magenta, Yellow and Black (CMYK), lots of them, giving an impression of continuity. These are the dots in dpi.

In practice, ppi and dpi are so closely related that they're often thought to be the same. Many times they are, but it's worth knowing that sometimes they're not.

There's also a vertical measure of density called lpi (Lines Per Inch) but it's not worth worrying about. If you're got your dpi high enough then you won't have lpi problems and you don't have to bother with it. Photoshop occasionally brings up the subject of lpi just to make sure amateurs continue to find it impenetrable. When it does, think of lpi as around half or two thirds of dpi and you won't go far wrong.
Conversion

The main problem with printing Web graphics is that as they're transferred to the print environment, ppi become dpi. Each pixel is seen as a one dot. And although 72 ppi is fine for looking at graphics on a screen, it's a very low dpi resolution for printing

Forget about printing through a browser. That's a special case and not a real print environment, though it does hint at some of the problems faced by a real print environment because the quality of graphics reproduction when printing through a browser is usually low.

What we want to consider are real print environments like QuarkXpress, Pagemaker and Word. With these, low dpi is a real issue.

For low quality printing at 150 dpi or maybe 300 dpi on an office printer, our 72 dpi Web graphic might just be OK, at a squeeze. For a magazine or brochure printed at 100% dpi, it's unlikely to be OK. The mismatch by a factor of eight or so is too big. When the Quark page goes through the RIP (Raster Image Processor) to make film for printing, the graphic is likely to get mangled and finish up looking very sorry for itself.

This is really down to the fact that the printing industry hasn't quite caught up with the Web. The best modern RIPs now deal with low resolution Web graphics quite well, but the majority still don't, and they're extremely expensive, so nobody is in a rush to replace them with new versions.

To get high quality output, these older RIPs must be spoonfed with higher resolution images. They want something of the order of 200 to 300 dpi to start with. So to get our graphic printed properly, somehow we have to boost its dpi to this kind of figure.
Complication

As we've already mentioned, graphics software like Photoshop generally sees one pixel as one dot, so it's effectively working in ppi and dpi at the same time. And it takes its ppi/dpi very seriously. If you increase the physical size of a print graphic, it will automatically reduce the dpi to compensate. Conversely, if you increase the dpi, the size of the graphic will reduce.

This is a pain in the ass, because it adds a big complication to our aim of boosting dpi. But it's done for the best of reasons. The software only has a limited amount of information from the graphics file to work with - that's the pixels/dots. If you go for low resolution, you're spreading them, so you get a bigger picture. If you try high resolution, they're bunched together and the picture is small.

If it's forced to deal with the picture in any other way - for example you want the size to remain the same but the resolution to go up - the software has to resample the image and create a brand new set of pixels/dots. There's usually a quality loss associated with resampling. It means tearing down the picture and rebuilding it from scratch, with all the pixels in different places.

That's why the software is reluctant to break out of the relationship between dpi and file size. It doesn't want to casually resample all the time and lose quality.
One resample

But we need a higher dpi/ppi for the graphic we're going to use in a brochure or magazine, so we're forced to resample.

And here's the real key to quality. Because resampling is bad, we must do it only once.

That means we need to know the final size of the graphic as it will be printed, and our resample should hit this final size fairly accurately, and at the same time raise the dpi.

The resampler in Photoshop is very good and used by most professionals. If you're running PaintShop Pro rather than Photoshop, congratulations. The resampler in PaintShop Pro is (in my opinion) slightly better than the resampler in Photoshop.

To resample a file, open it in Photoshop and select Image > Image Size. What happens next depends on the version. If you've got a button marked auto, first enter the final size in inches or centimeters. Then press Auto. Now choose an appropriate screen or go with the default of 133. Select Best Quality and OK. Your image will be resampled to 266 dpi or double whatever you entered as the screen.

If you don't have an Auto button, first choose your dpi (266 if you can't think of a better number) and then your file size. Then press OK. If you have a Retain File Size button and you want to keep the original physical file size, this is the time this button comes into play.

In either case, if you get anything wrong, revert to the original file and start again.
Triple Resampling

This sounds pretty simple, but you might follow the rules and still find that your Web graphic looks lousy when it's printed.

Why?

Usually because somebody else has also resampled it. And with professional printing, that somebody else is probably your print bureau or printer.

Many printers and bureaus have a habit of reformatting every picture before they send pages to the RIP. They do this to make sure the pictures don't foul up and waste film. For normal print graphics at high resolution, the quality difference can be negligible.

Low resolution pictures are even more likely to get this treatment, because they're more likely to foul up.

So in the end, your low resolution Web graphic may get resampled three times. Once by you as you attempt to get the size right and bring the resolution up, once by the bureau because they want to make sure the RIP won't foul up, and once by the RIP itself, which is effectively a resampler too.

Now you know why your printed graphic looks so bad.
What Can You Do About It?

You have to try to get the number of resamples down. Ideally, you want only your printer's state-of-the-art RIP to resample. Ask your printer if their RIP will accept low resolution Web Graphics. When they say yes, try to work out if they mean it. I've nothing personal against printers, but many of them do seem to bend the truth in the interests of making money. They'll say "Yes, our RIP takes low res pictures," and then secretly they'll change the resolution on the picture (resample it) before it goes through.

They'll also ask you to send all pictures at a minimum of 200 dpi, and then resample every one of them to bring the resolution up to 100% dpi before running them through the RIP. Not all printers, but some.

Again, this is triple resampling and you want to find out if it's happening and avoid it if possible.

There's only one other thing you can do, which is to improve the sharpness of the graphic after it's been resampled, using a filter. In Photoshop, the one to use is Filter > Sharpen > Unsharp Mask. If you've not used it before, you should be able to get the hang of it after a few minutes by playing with the settings. As a general guide, the Threshold setting will usually be in the range 8-25, the Radius 1-4 pixels and the Amount between 10 and 50 percent. Using Unsharp Mask, even for just a minor tweak, will invariably improve the quality of the graphic in print.

So here are the key elements to getting your Web graphics printed at high quality:

1. Don't expect too much. There's a limit to how big you can print something that's inherently low quality. Around 50% original size is the maximum.

2. Somebody will probably need to resample the graphic to bring the dpi up to a decent level. If that's you, make sure you only do it once, and at the same time get the size roughly right.

3. Try to ensure that your printer isn't going to change the resolution (resample) yet again before your picture goes through the RIP. If they tell you it's essential, see if they can take the picture from you in its raw, low resolution form and do the single resampling themselves.

4. If you can find a printer with a RIP that can deal properly with very low resolution pictures, you've hit the jackpot.

5. Learn Unsharp Mask and use it whenever you resample.

[brahym]

memang betul tu..memang disuggestkan utk print guna 300dpi. So bilangan pixel yang mencukupi untuk 4R [4X6] ialah 1200 X 1800 atau bersamaan dengan 2.16mega pixel. Tapi kalau nak print 8R, at least kena ada 2400 X 3600 atau bersamaan dengan 8.64 efective megaixel. Even canon 350d pun cuma 8MP dan 20d = 8.2mp still tak mampu memberi saiz sebenar 8R 300dpi.

Ini akan menyebabkan gambar akan diprint dgn resolusi bawah dari 300dpi..So ingatlah bahwa jika nak print gambar besar2 dengan dpi mencukupi, dptkan segera DSLR yang mempunya MP yang tinggi. Tapi kalau just nak print 4R ok ler kalau pakai 3MP pns jer.

p/s - bayangkan kalau nak print guna med format printer 16 X 24". Pixel yang diperlukan ialah 4800 X 7200 atau bersamaan dengan 34.56MP.

[yokozuna]

memang betul tu..memang disuggestkan utk print guna 300dpi. So bilangan pixel yang mencukupi untuk 4R [4X6] ialah 1200 X 1800 atau bersamaan dengan 2.16mega pixel. Tapi kalau nak print 8R, at least kena ada 2400 X 3600 atau bersamaan dengan 8.64 efective megaixel. Even canon 350d pun cuma 8MP dan 20d = 8.2mp still tak mampu memberi saiz sebenar 8R 300dpi.

Ini akan menyebabkan gambar akan diprint dgn resolusi bawah dari 300dpi..So ingatlah bahwa jika nak print gambar besar2 dengan dpi mencukupi, dptkan segera DSLR yang mempunya MP yang tinggi. Tapi kalau just nak print 4R ok ler kalau pakai 3MP pns jer.

p/s - bayangkan kalau nak print guna med format printer 16 X 24". Pixel yang diperlukan ialah 4800 X 7200 atau bersamaan dengan 34.56MP.

bang brahym, kalau cam 20D kan...kalau ambik RAW...saiz nyer ialah 2336 X 3505 pixels tapi kt dia nyer resolution tu ialah 350 dpi.....
so dr segi saiz mmg tak cukup (menghampiri) tapi resolution tu dah lebih...so macamaner ni?

[AyAres151]

yoko..

rasanya la.. utk print 8R pada reso dan size yang tuh dah mencukupi... cuma detailsnya tak sama la dengan yang lebih besor sizenya.. mungkin yg 10mp punya camera tuh bleh hasilkan yang lebih details..

[helmyemran]

mungkin sebagai photographer pro, brahym mementingkan kualiti pada printingnya. tp biasanya pada graphic designer, kita akan anggarkan jarak mata yang melihat dengan artwork yang terhasil. orang biasa tak tengok dekat2. kalau cam size 16x24' tu, kalau guna 150 dpi, bole dpt 8.64 mp saja.

format file juga bole menentukan kualiti gambar dan sizenya. tak guna kalau guna 300 dpi, tp save dgn compression tinggi. ini cuma pendapat aku. bagus gak bincang isu nie. dpt tau sensitiviti photog pada kualiti gambar.

[brahym]

memang betul tu..memang disuggestkan utk print guna 300dpi. So bilangan pixel yang mencukupi untuk 4R [4X6] ialah 1200 X 1800 atau bersamaan dengan 2.16mega pixel. Tapi kalau nak print 8R, at least kena ada 2400 X 3600 atau bersamaan dengan 8.64 efective megaixel. Even canon 350d pun cuma 8MP dan 20d = 8.2mp still tak mampu memberi saiz sebenar 8R 300dpi.

Ini akan menyebabkan gambar akan diprint dgn resolusi bawah dari 300dpi..So ingatlah bahwa jika nak print gambar besar2 dengan dpi mencukupi, dptkan segera DSLR yang mempunya MP yang tinggi. Tapi kalau just nak print 4R ok ler kalau pakai 3MP pns jer.

p/s - bayangkan kalau nak print guna med format printer 16 X 24". Pixel yang diperlukan ialah 4800 X 7200 atau bersamaan dengan 34.56MP.

bang brahym, kalau cam 20D kan...kalau ambik RAW...saiz nyer ialah 2336 X 3505 pixels tapi kt dia nyer resolution tu ialah 350 dpi.....
so dr segi saiz mmg tak cukup (menghampiri) tapi resolution tu dah lebih...so macamaner ni?

Adik yokuzona..hheheh... walaupun dpinya tinggi, tapi pixel size tak besar so maximum print size dia pun tak besar...

mcm 20d tu sebab res dia 2336 X 3505 so akan dapat samada
1. 6.674" X 10.014" @ 350dpi
2. 7.787" X 11.683" @ 300dpi [still kurang dr 8R]
3. 15.573" X 23.367" @ 150dpi

so maknanya..kalau nak print besar..dpinya akan kurang..

[brahym]

mungkin sebagai photographer pro, brahym mementingkan kualiti pada printingnya. tp biasanya pada graphic designer, kita akan anggarkan jarak mata yang melihat dengan artwork yang terhasil. orang biasa tak tengok dekat2. kalau cam size 16x24' tu, kalau guna 150 dpi, bole dpt 8.64 mp saja.

format file juga bole menentukan kualiti gambar dan sizenya. tak guna kalau guna 300 dpi, tp save dgn compression tinggi. ini cuma pendapat aku. bagus gak bincang isu nie. dpt tau sensitiviti photog pada kualiti gambar.

Ni memang aku setuju. Macam TV besor kat depan jalan pudu tu tak? Kalau jauh nampak lawa tapi bila dekat nampak sangat LED dia. Gambar besar biasanya orang perati jauh2 jer. Tapi kalau boleh2nya...gambar cam 16X24" tu besar ler dpinya sebab kalau diframekan, maybe ada org yang dok perati dekat2 cam aku ni...gambar dlm majalah tu pun aku selalu perati dekat2..hehhe

then kalau sayang sgt kat gambar anda..jgn save dlm format jpg dgn high compression cam helmi cakap tu. Gunakan jer format tiff...kalau nak jpg gak..bantai jer compression zero atau '12' kat PS tu..kekke

my 2 cent

[cgmulia]

aku setuju ngan brahym. coz bukan semua org akan gi tgk dgn teliti.
semua tu takkan dpt dilihat dengan jelas sekiranya dari jauh.. namun bg org seperti aku dan brahym.. mmg akan perhati dekat2... pastu tgk kelemahan pada printing gambar itu sendiri. maybe dari sudut grafik kot...
aku sendiri buat mcm brahym buat dan aku sendiri tak tau kenapa aku berbuat demikian.

[AyAres151]

nak tanya bro brahym.. camne nak save jpg tuh dengan compreassion zero atau 12??

bleh terangkan details tak camne takmmoh comprese semasa Save as JPG tuh..

[brahym]

Masa save tu letak quality dia maximum cam kat bawah ni..

http://img456.imageshack.us/img456/8869/save1en.jpg

[AyAres151]

owh..ingatkan ada cara lain ...hehehe... sorry tanya soalan budus tu.. kot2 ada setting lain lagi jerk..

erm.. yang size @ 56.5kbps tuh ada effect tak kalu ubah?

[brahym]

yang kat bawah tu just calculation untuk file downloading kalau upload dia kat web. dan juga anggaran saiz file yang akan disave kelak.

[AyAres151]

owh...camtuh rupanya... jahil gak ese bab2 nih.. wakkkaa

Tq cikgu..

[cgmulia]

ayares..
maybe bg ko soklan tu soklan budus...
tp bg org yg tak pernah perasan benda tu.. satu ilmu yg baru bg diorg.
sebenarnya ko telah membantu dlm proses penyampaian ilmu secara tidak langsung.
benda remeh kadang2 org tak tanya tp kadang2 org pun tak tahu.
tak gitu brahym????

[yokozuna]

nak tanya bro brahym.. camne nak save jpg tuh dengan compreassion zero atau 12??

bleh terangkan details tak camne takmmoh comprese semasa Save as JPG tuh..

setahu aku kalau dh jpeg ni mmg file tu dlm btk sudah di compress..cume quality zero atau max.. so kalau tak nk compress sms nk save as jpeg tak leh rasenye.....kalau nk quality lg elok save dlm tif

[helmyemran]

yup, aku setuju dgn yokozuna. setiap kali kita save as .jpg, kualiti gambar akan dikurangkan sebab tu tugas jpg "memadat". cuma tahap pemadatan tu yang ditanya pada kita sama ada tinggi atau rendah. kalau nak copy file gambar jpg, lebih baik copy paste dlm window drpd save as dlm software. tu nasihat yg aku baca dua tiga thn lepas, lupa dah url site tu.

dulu kalau nak anta printing brochure ke, buku ke, disuruh pakai gambar tiff. then tuka mode CMYK, supaya kualiti gambar terjamin. jpg was designed for web actually. skang aku tgk, sykt printing tak kesah sume tu. aku pun dah lama tak buat dtp. dah bole kot.

[brahym]

kalau nak gamba kita berkuality sentiasa...save ler dlm bentuk raw. Tapi ada sesetngah high end model yang save dlm tiff.

[AyAres151]

Oh ya.. nak tanya lagi la... Katakan kita shoot guna RAW... bleh ke kita edit guna photoshop tuh tanpa save as ke lain... maknanya.. kita save sahaja... agar ia tetap RAW..

atau bila kita dah open in PS... ia takleh save sebagai RAW lagi?

ok..

soalan kedua :

Kalu shoot in RAW... bleh ke kita terus antor kedai utk print.. maksud ese.. kedai gambar punya machine leh baca ek RAW format atau Tiff format??

[cgmulia]

soklan kedua aku bleh jawab
soklan pertama aku tak penah try... so aku takleh jawab
jawapannya...... buleh!

[AyAres151]

larr... CG.. kan dah ada d70s di tangan... shoot la RAW sekeping... try la edit in PS... baru bleh jawab soalan pertama tuh..hehehe.. apa laga..gi shoot sekarang.. hehehee..

[yokozuna]

Oh ya.. nak tanya lagi la... Katakan kita shoot guna RAW... bleh ke kita edit guna photoshop tuh tanpa save as ke lain... maknanya.. kita save sahaja... agar ia tetap RAW..

atau bila kita dah open in PS... ia takleh save sebagai RAW lagi?

ok..

soalan kedua :

Kalu shoot in RAW... bleh ke kita terus antor kedai utk print.. maksud ese.. kedai gambar punya machine leh baca ek RAW format atau Tiff format??

ermm, setakat ini aper yg aku belajar, orang akan edit balik gbr yg diambil dlm btk RAW sbg contoh utk saturation tu di naikkan lg, utk contrast tu dinaikkan lagi dsb la.. pastu baru kiter akan print..
dan lepas tu orang akan convert to jpg or tiff dsb. utk view kt monitor dsb la..
so b4 print tu adekah org kedai gbr akan edit gbr2 kite b4 diorang print?
Utk read format RAW bg berlainan model camera adelah berlainan software nya, walaupun ps cs2 terkini boleh read sbrg format RAW...
tapi mengikut pendapat aku, utk edit file RAW better guna software yg diberi bersama kamera ( sms beli) drpd edit guna ps cs2...
so adekah pernyataan aku ni betul atau salah?
apekah software yg digunakan oleh org kedai utk print gbr kite?

[AyAres151]

blom menjawab soalan pertama lagi tuh..

sebenarnya maksud ese.. kalu katakan kita dah Open file RAW using PS CS2 atau any photoeditor... adakah lepas kita open dan edit.. adjust apa2 yg patut.. adakah kita leh save editing kita dalam format RAW lagi utk bawak gi print kat kedai selepas editing tadi??

atau dah tak boleh save dalam format RAW lagi dah selepas editing?

dan

adakah format RAW nih hanya di hasilkan oleh camera jerk ker?

[yokozuna]

blom menjawab soalan pertama lagi tuh..

sebenarnya maksud ese.. kalu katakan kita dah Open file RAW using PS CS2 atau any photoeditor... adakah lepas kita open dan edit.. adjust apa2 yg patut.. adakah kita leh save editing kita dalam format RAW lagi utk bawak gi print kat kedai selepas editing tadi??

atau dah tak boleh save dalam format RAW lagi dah selepas editing?

dan

adakah format RAW nih hanya di hasilkan oleh camera jerk ker?

setahu aku setakat ini, bila dh edit kt ps cs 2 tu, boleh save dlm format RAW tapi photoshop RAW. dan aku rase format ni berlainan drpd format RAW drpd kamera tu..
soalan : atau dah tak boleh save dalam format RAW lagi dah selepas editing?aku rase yg ni, file RAW drpd kamera kite tu akan kekal dlm bentuk asal sampai bile2 selagi kite tak delete.makna nye walaupun bila dh convert ke jpeg dsb, kita still boleh edit blk menggunakan file RAW tadi utk mase2 yg akan dtg. so mengapa nk save dlm bentuk RAW lagi. sedangkan file RAW tadi still boleh digunakan. makna nyer data2 drpd file RAW asal tadi tidak diusik, cuma menjadi satu salinan baru dlm format jpeg dsb apabila diconvert.

adakah format RAW nih hanya di hasilkan oleh camera jerk ker?
biasanya kamera akan record ke dlm memory dlm btk jpeg @ RAW @ RAW+jpeg(yg ni aku tak guna sbb aku takpaham sgt). so kalau kamera tu record dlm btk jpeg, gbr tu benarnye dh di compress drpd kamera tu lagi. tetapi kalau dlm bentuk RAW, kamera tak adjust sedikit pun samada compression, color tone, quality etc.

[yokozuna]

kalau nak gamba kita berkuality sentiasa...save ler dlm bentuk raw. Tapi ada sesetngah high end model yang save dlm tiff.

kurang jelas...edit & save dlm bentuk RAW? ke save or record dlm btk RAW kpd CF card?
pd pemahaman sy, bukankah file asal drpd kamera adalah sentiasa dlm bentuk RAW (jika di shoot dlm btk RAW)..convertion yg kite buat drpd file RAW kpd format jpeg,tiff dsb tu setahu saye seolah2 copy dprd file RAW tadi dan dicompress serta di simpan kpd satu salinan lain dlm format jpeg, tiff etc. maknenya file RAW asal drpd camera adalah still RAW selagi tak di delete...

Understanding RAW files (http://www.luminous-landscape.com/tutorials/understanding-series/u-raw-files.shtml)

[AyAres151]

jadi.. kalu dah shoot RAW... tp kita nak edit... pastu nak antar kedai cuci..
nak save sebagai apa plak selepas di edit?

save as tiff ke atau bleh save sebagai RAW lagi utk kekalkan quality gambar selepas edit?

sbb kita shoot tak semestinya terus lawa sbb bukan pro photog..kalu pro..shoot RAW..antar terus kedai cuci tanpa editing..hehhe

[brahym]

Lor...penin kepala eden baca..kekke..aku try jawab la yer..ntah betul ntah idak.

1. Shoting raw - maknanya hasil gambar tu tanpa-in-camera-editing. So takde edit dilakukan oleh camera samada WB, exp comp, sharpness, etc. Tujuannya memang nak suruh kita post editing dgn software kelak. So leh guna PS, nikon capture yang canon bg tuh. Lepas edit, kita save ler dlm bentuk lain spt tiff atau jpg. Jgn save as kat raw tu [aku rasa tak boleh kot overwrite raw ni] sebab takut nanti kita nak adjust lagi raw tu.

2. Lepas gambar raw tu save dlm btuk tiff atau jpg..antor ler g kedai untuk cuci. Tak pernah dengor kedai yang cuci RAW sebab ada byk jenis raw. Contohnya nikon guna .NEF, canon .CRW...kalau KM, oly, pentax..dan bermacam2 lg..so byk sgt format.

my 2 cent.

[helmyemran]

huh, bagus soalan AyAres tu. barula nak explore RAW format dlm kamera aku nie.

[cgmulia]

ayares...
aku takleh buat lagi...
tak dan
pc aku aku tak guna nikon software tu..
so. ps aku tak detect raw image tu..

tp aku rasa.. pendapat aku sama ngan brahym...
cuma aku penanh cuci raw kat kedai yg selalu aku cuci, dia pakai 350D ngan 300D, dan bila aku antar raw (NEF)aku dia kata boleh....
maybe sesetengah kedai je kot.. aku pun tak pasti coz aku tak test kedai2 lain.

my seposen

[brahym]

depnd kedai tu samada dia pakai PC CS dgn raw converter plugin..

[brahym]

Defining Resolution
Written by Ben Horne (04/23/2005)

Today, April 23 2005 marks the boiling point. That's right, today I've reached my limit for reading improper information regarding resolution. There is a lot of confusion about all those three letter acronyms regarding resolution. You have LPI, SPI, PPI, and everyone's favorite, DPI. These terms are often mistakenly interchanged. Worse yet, some people give up and just say DPI for every form of resolution. We need to get this straight people, it's really not all that tough. Here is how the terms break down:

LPI: Lines Per Inch This term is used in the offset printing industry. Magazines and newspapers are the best examples. Images are formed by different sized dots that are arranged in rows (called lines). Think of it like a pearl necklace with pearls that vary greatly in size. LPI is a measure of how many lines of dots (or pearl necklaces) are contained within an inch. This term doesn't really come into play unless you're either in the printing industry, or you're a geek.

SPI: Samples Per Inch This term is used for scanning. It determines how many samples are contained within one inch. However, this is also the source of confusion for most people. The scanner software often lists "DPI" in the options. Therefore, people assume DPI (which is printer resolution) is a universal phrase for resolution. Not true!

DPI: Dots Per Inch DPI is strictly a printing term. It will determine the print quality of an OUTPUT device. For example, your inkjet printer has the ability to print at a given DPI setting. You'll often see numbers like 1440, or 720, or similar numbers. This has to do with how many dots of ink are put down within an inch.

PPI: Pixels Per Inch Alright, get out your highlighter and mark this portion of your computer monitor. This is an important one. PPI is a measure of how many pixels will fit within a linear inch. This is intended mostly for monitor resolution, but it also has some serious implications when translating a pixel based file to another medium such as... a print! Your computer monitor is likely around 72 PPI. However, 72 PPI is not anywhere near photo quality in print. You'll be able to see each pixel in print.
Ok, so now we have defined the major terms. Let's put them to use. Images from digital cameras are strictly X by Y pixels. They have no inherent resolution or print size. The size of the print will depend on how many pixels will be crammed into a linear inch of print. So in other words, you could say that the print quality will depend on the number of Pixels Per Inch. Let's go over some of the more popular questions that we find on the internet forums.

I just paid $1500 for a new digital camera, and it only shoots images at 72 DPI!. Did you spot the error already? If not, refer to the definitions above. DPI has to do with printer resolution. Right off the bat, that's an improper use of the term. Setting that aside, most cameras these days do not tag the image files with a default PPI setting. Therefore, they default to 72 PPI in software.

Let's take the Canon EOS 1D mkII for example. It is an 8 Megapixel Camera with files that measure 2336 x 3504 pixels. If this file is not tagged with a default PPI, it will become 72 when you open it in photoshop. As a result, the print will measure 32" x 48". Is 72 PPI photo quality in print? No way! However, at that quality level, it would make a massive enlargement! If you blew a 35mm slide up to that size, it probably wouldn't be photo quality either. However, if the PPI was set to 240, it would make a 9.7" x 14.6" print. 300 PPI (Not DPI folks) is generally known as photo quality. However most inkjet printers can't see anything more than about 240 PPI for photos.

Since 300 PPI has really become the industry standard for photo quality, people will often ask how big a print they can make from their digital camera at that resolution. There is no real mystery here, just crunch some numbers. Let's take the 1DmkII as an example again. Divide the pixel dimensions by 300, and you'll get your 300 PPI print size. The answer is 7.87" x 11.68". Good luck finding a frame that size. If you want to print at 8x10, you'll need to adjust your print dimensions in photoshop with the resample image box unchecked. Set the short side to 8", and the long side will become 12" at a PPI of 292. That's still way above 240 PPI, so the print quality will be excellent.

What if you want to make a 13x19 print at 300 PPI from the 1DmkII? As illustrated above, you're not going to even get a 8x10 at 300 PPI, so something has to give. Either you need to use a lower PPI setting which will lower the overall image quality, or you need to interpolate (stretch) the file. Interpolation is a method of enlarging a file. You do not gain any real resolution by doing this, but it's a good way to avoid printing a file with a low PPI setting where the pixels will become visible in print. An interpolated file will soften up a bit, but that's much better than seeing tiny squares. For this, you need to check the resample image box in photoshop. Now, enter 13x19 as your print dimensions, and enter a PPI of 300. You'll see that the pixel dimension will increase to 5850 x 3900. The file will now print huge , but it was not a true resolution increase. The file was only interpolated.

Let's recap on the points I made in this article. There are several terms for resolution depending on the input/output device. DPI is not a catch all phrase. Often times, people really mean PPI when they say DPI. Digital camera files are measured in pixels, and have no inherent print size. However, the PPI setting (which you can adjust to whatever you want) will translate the pixel dimensions into a print size. 240 PPI is about all most inkjet printers can resolve, though 300 PPI is a very common number in the industry.

[helmyemran]

article nie cam nak suruh sume org tukar istilah dpi ke ppi. dpi hanya untuk printing? cam tu, adobe photoshop pun kena tukar istilah dlm dialog box image size tu la. hmm... mungkin aku tak faham lagi kot. bro brahym, ada penulis tu bg bibliography, atau dia tulis atas pendapat sendiri?

[AyAres151]

owh....dah paham dah... jadi.. utk lebih mementingkan kualiti.. lepas edit file RAW>.btter save as tiff... kan..

[brahym]

So kengkawan..sapa yang leh kata megapixel tinggi tak penting?..sila angkat tangan...heheheh

[lanun8]

BUMP 4 a good thread