Image Manipulation (Watermarking, Resizing and Thumbnails)

[Leonard Challis]

Good morning everyone

I am currently doing quite a large project in VB6 and ACCESS for college,
for a Photographers company assignment. I am posting here to see if anyone
has any advice on what I might want to try to counter the problems I seem to
be facing...

The only area of the project I am struggling on is the graphical side.
Basically, I need to take in a load of large photographs, create a thumbnail
for each, create a preview size for each, and then watermark the preview
size. The thumbnail size and preview size images will later be uploaded to
the web server so customers can view them.

Currently I am using two different methods for the different tasks. For
resizing, including preview size and thumbnails I have been using FreeImage
which seems to work pretty well actually. It hasn't been easy to find (free)
watermarking .DLLs/modules/activeX controls though, and I am currently using
something I found on a forum, which basically takes two pictures boxes and
loops through each pixel and combines the two picture boxes creating the
watermark. It is very hit and miss.. but it is kind of the best thing I can
use right now.

What I was wondering is does anyone know of a good method of doing the tasks
I want without having to include more than one or two .DLLs or something
like a control that supports all these features. There are loads out there I
have found on Google, but being a student I can't afford the huge price
tags! Any suggestions or ideas would be welcome and thanks for your time.

Lenny Challis

FYI: Here is some examples of the code I am using/referencing to make my
own:

___________________
Watermarking
___________________
Option Explicit

' Return (A * clr1 + (255-A) * clr2)\256.
Private Function CombineColors(ByVal clr1 As OLE_COLOR, ByVal clr2 As
OLE_COLOR, ByVal A As Byte) As OLE_COLOR
Dim r1 As Long
Dim g1 As Long
Dim b1 As Long
Dim r2 As Long
Dim g2 As Long
Dim b2 As Long

b1 = Int(clr1 / 65536)
g1 = Int((clr1 - (65536 * b1)) / 256)
r1 = clr1 - ((b1 * 65536) + (g1 * 256))

b2 = Int(clr2 / 65536)
g2 = Int((clr2 - (65536 * b2)) / 256)
r2 = clr2 - ((b2 * 65536) + (g2 * 256))

r1 = (A * r1 + (255 - A) * r2) \ 256
g1 = (A * g1 + (255 - A) * g2) \ 256
b1 = (A * b1 + (255 - A) * b2) \ 256

CombineColors = r1 + 256 * g1 + 65536 * b1
End Function

Private Sub Command1_Click()

DrawWatermark Picture1, picBackground, (picBackground.ScaleWidth / 2 -
Picture1.ScaleWidth / 2), (picBackground.ScaleHeight / 2 -
Picture1.ScaleHeight / 2)

End Sub

' Copy the watermark image over the result image.
Private Sub DrawWatermark(ByVal wm_pic As PictureBox, ByVal bg_pic As
PictureBox, ByVal x As Integer, ByVal y As Integer)
Const ALPHA As Byte = 128
Dim transparent As OLE_COLOR
Dim wm_clr As OLE_COLOR
Dim bg_clr As OLE_COLOR
Dim new_clr As OLE_COLOR
Dim px As Integer
Dim py As Integer

' Get the transparent color.
transparent = wm_pic.Point(0, 0)

' Combine the images.
wm_pic.ScaleMode = vbPixels
bg_pic.ScaleMode = vbPixels
For py = 0 To wm_pic.ScaleHeight - 1
For px = 0 To wm_pic.ScaleWidth - 1
wm_clr = wm_pic.Point(px, py)
If wm_clr <> transparent Then
bg_clr = bg_pic.Point(x + px, y + py)
new_clr = CombineColors(wm_clr, bg_clr, ALPHA)
bg_pic.PSet (x + px, y + py), new_clr
End If
Next px
Next py
End Sub

Private Sub Form_Load()

End Sub