[khyu2862]

小弟是一名新手...有一個問題想請問各位..
通常2M嘅相機有1600x1200解像度,3M有2048x1536,4M有2272x1704,咁5M就有2592x1944..好喇咁如果我張3M相機嘅解像度減去2M相機嘅解像度ja係 (2048-1600)=448,(1536-1200)=336,咁ja係3M同2M兩部機嘅解像度相差448x336,如果再計落去
4M-3M就相差 224x168
5M-4M就相差 320x240
如果咁計差額最大就係3M-2M....咁樣係唔係代表其實2M同3M嘅相機影出黎D相其實係相差最大呢?

唔知你地明唔明我講乜呢^^
謝謝

[pl1]

你說得絕對正確. 其實從3M 到4M 或是從 4M 到 5M 的分別是很少的. 我聽過有人說什麼 3M 可印 4R, 4M 可印5R, 5M 可印 8R. 簡直是胡說八道. 3M 和 5M 的長和闊只有 25% 的差別, 但 4R 和 8R 卻有100%的差別!

[khyu2862]

咁ja係話一般買部3M解像度嘅相機都夠晒用....^.^

[Preston]

so how big can a 2272x1704 image print out with BEST viewing quality?

[sing342]

以上的計法只是一個約數，其實以4比3成像計算，1600x1200是不足2百萬像素的，而2048x1536是大過3百萬像素，你可以將以上數值相乘便知1600x1200是1920000，而2048x1536是3145728
所以用正確的像素數目計算即2百萬是1633x1224.7 而3百萬是2000x1500，如果同樣以這方法計算3M-4M……5M。會得出相同比例的數值。因此像素愈多所放大的呎吋愈大

[MN56]

< 通常2M嘅相機有1600x1200解像度,3M有2048x1536,4M有2272x1704,咁5M就有2592x1944..好喇咁如果我張3M相機嘅解像度減去2M相機嘅解像度ja係 (2048-1600)=448,(1536-1200)=336,咁ja係3M同2M兩部機嘅解像度相差448x336,如果再計落去
4M-3M就相差 224x168
5M-4M就相差 320x240>>
khyu2862兄：

我想閣下只是在數學運算上出現錯誤而已。假設3M相的2048是"a"，1536是"b"(即3M=a x b)；另外，2M的1600是"c"，1200是"d"，即2M=c x d。因此3M-2M的pixel差是(ab)-(cd)，但你的計算法卻寫成(a-c) x (b-d)，但是，從代數學中知道：(ab)-(cd)不等於(a-c) x (b-d)，所以你才會有4M-3M不等於3M-2M的問題存在。事實上，每次這樣的計算，差距都一要大概為1M左右。

[kwkyiu]

that's right, but I think khyu2862's concern is on H x W, but not the area

here is a table for ref.
area H and W
2M->3M +50% +22.5%
2M->4M +100% +41.5%
2M->5M +150% +58%
3M->4M +33.3% +15.3%
3M->5M +66.7% +29.2%
4M->5M +25% +11.8%


[kwkyiu]

also, for print outs

3R(3.5inches X 5 inches)
4R(4inches X 6 inches)
5R(4inches X 7 inches)
6R(6inches X 8.5 inches)
8R(8inches X 10 inches)
8RC(8inches X 12 inches)

assume using 300dpi
2M(1600 X 1200 -> 5.3 X 4) fits on 3R with some crop
3M(2048 X 1536 -> 6.8 X 5.1) fits on 4R with some crop, even good for 5R
4M(2360 X 1770 -> 7.85 X 5.9) fits on 5R with some crop, even good for 6R
5M(2640 X 1980 -> 8.8 X 6.6) fits on 6R with some crop, too far from 8R
if you really want 8R, you need 8M(3200 X 2400 -> 10.6 X 8)

[MN56]

我所講的axb 和 cxd是計算number of pixels，而不是面積。同一number of pixels常有不同面積，即pixels size 不同。反之亦然，同一CCD面積不等於number of pixels相同，所以，difference of number of pixels同H 及W沒有必然關係。

[kwkyiu]

sorry, area and (H and W) is just and analogy.
not related to the actual size of pixel or the CCD.

as the first poster is a newbie,
so I think this his concern will be what the photo looks like
on the screen and/or the print outs

[Alan Tse]

Is there any differences in picture quality for a 3M and 2M photos printed in 4R ?

[MN56]

For printing, 150dpi is enough..

[6x4.5]

不知所謂,一遢胡塗..

ppi (pixel per inch) 同 dpi (dot per inch) 無絕對關係
請勿將兩者混淆

[khyu2862]

唔...真係學左唔小野...上面我寫果條咁嘅數學題我都唔知有冇錯ka...我只是計算下 H同W..相差幾大..就唔係計佢ga面積.. 咁發現其實3M同4M ga相機其實相差係最細..所以我問下各位高手ja ma ^-^

[Preston]

so which size I can choose for 2272x1704 with NO CROP?